WO2024096594A1 - All-solid-state lithium-ion secondary battery - Google Patents
All-solid-state lithium-ion secondary battery Download PDFInfo
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- WO2024096594A1 WO2024096594A1 PCT/KR2023/017308 KR2023017308W WO2024096594A1 WO 2024096594 A1 WO2024096594 A1 WO 2024096594A1 KR 2023017308 W KR2023017308 W KR 2023017308W WO 2024096594 A1 WO2024096594 A1 WO 2024096594A1
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- negative electrode
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- electrode active
- solid
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Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
- H01M10/0562—Solid materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
Definitions
- the present invention relates to an all-solid lithium ion secondary battery.
- an all-solid lithium ion secondary battery for example, it is known that a metal layer formed of a metal that forms an alloy with lithium is provided as a negative electrode active material layer, and an interface layer made of amorphous carbon is provided on the negative electrode active material layer.
- metallic lithium precipitates between the amorphous carbon interface layer and the negative electrode active material layer when charging, and when discharging, the metallic lithium is ionized and moves toward the positive electrode.
- the present invention was devised to solve the above problems of the prior art,
- the purpose is to provide an all-solid lithium ion secondary battery that does not require high external pressure, suppresses dendrite formation, and has excellent discharge capacity and lifespan characteristics.
- It includes an anode, a cathode, and a solid electrolyte interposed between the anode and the cathode,
- the negative electrode includes a negative electrode current collector and a negative electrode active material layer,
- the negative electrode active material layer includes carbon material and Ag, and provides an all-solid lithium ion secondary battery including two or more layers.
- the all-solid lithium ion secondary battery of the present invention does not need to apply high external pressure, suppresses dendrite formation, and provides excellent discharge capacity and lifespan characteristics.
- 1 to 4 are cross-sectional views schematically showing the structure of the all-solid lithium ion secondary battery of the present invention
- Figure 5 is a graph showing the results of measuring the cycle characteristics of the all-solid lithium ion secondary battery of Example 7 and Comparative Example 2 of the present invention
- Figure 6 shows an SEM image of the cathode of Example 6 of the present invention.
- Figure 7 is a graph showing the particle size distribution of the carbon material-metal composite of the present invention.
- the term “combination” includes mixtures, alloys, reaction products, etc., unless specifically stated otherwise.
- terms such as “first” and “second” do not indicate order, quantity, or importance, but are used to distinguish one element from another element.
- the all-solid-state lithium ion secondary battery 100 of the present invention includes a positive electrode 10, a negative electrode 20, and a solid electrolyte 30 interposed between the positive electrode and the negative electrode,
- the negative electrode includes a current collector 22 and a negative electrode active material layer 24,
- the anode active material layer 24 includes carbon material and Ag, and is characterized by including two or more layers.
- the two or more layers include two layers including a carbon material and Ag, and the two layers include different Ag contents.
- the layer disposed adjacent to the negative electrode current collector 22 is adjacent to the solid electrolyte 30. It may be characterized by a higher Ag content ratio than the disposed layer (e.g., Figure 1, 24b). All-solid-state batteries with this structure can provide better discharge capacity and lifespan characteristics.
- the layer disposed adjacent to the negative electrode current collector is 1.5 to 10 times, preferably 2 to 8 times, 2 to 4 times, or 2 to 3 times larger than the layer disposed adjacent to the solid electrolyte. It may contain double Ag.
- the layer disposed adjacent to the negative electrode current collector may include 20 to 80% by weight, 20 to 60% by weight, or 25 to 55% by weight of Ag based on 100% by weight of the total negative electrode active material layer, and the negative electrode active material layer It may contain 20 to 80% by weight or 40 to 80% by weight of carbon material based on 100% by weight of the total.
- the negative electrode active material layer disposed adjacent to the negative electrode current collector may further include a binder, in this case, 20 to 75% by weight of Ag, 20 to 75% by weight of carbon material, and 1 to 10% by weight of binder. It may also include 25 to 55% by weight of Ag, 40 to 73% by weight of carbon material, and 1 to 10% by weight of binder.
- the layer disposed adjacent to the solid electrolyte may include 10 to 60% by weight, 15 to 40% by weight, or 15 to 30% by weight of Ag based on 100% by weight of the total negative electrode active material layer, and the entire negative electrode active material layer Based on 100% by weight, the carbon material may be included at 40 to 90% by weight, 60 to 85% by weight, or 70 to 85% by weight.
- the negative electrode active material layer disposed adjacent to the solid electrolyte may further include a binder.
- a binder may include 10 to 55% by weight of Ag, 40 to 85% by weight of carbon material, and 1 to 10% by weight of binder. It may also include 15 to 30% by weight of Ag, 65 to 83% by weight of carbon material, and 1 to 10% by weight of binder.
- the two layers including the carbon material and Ag may each independently have a thickness of 1 ⁇ m to 50 ⁇ m.
- the all-solid lithium ion secondary battery of the present invention contains the entire negative electrode active material in addition to the two layers 24a and 24b containing the carbon material and Ag. It may further include a layer 24c containing 0 to 5% by weight, or 0 to 2% by weight, of Ag based on 100% by weight. The layer may further include 95 to 100% by weight or 98 to 100% by weight of carbon material.
- the layer when the layer includes a binder, it may include 0 to 5% by weight of Ag, 90 to 99% by weight of carbon material, and 1 to 10% by weight of binder, and may also include 0 to 2% by weight of Ag and carbon material. It may include 90 to 99% by weight, and 1 to 10% by weight of binder.
- the layer containing 0 to 5% by weight of Ag and a carbon material is formed as a layer that does not contain Ag.
- the layer may further include a binder, and in this case, it may include 90 to 99% by weight of carbon material and 1 to 10% by weight of binder.
- the layer 24c containing 0 to 5% by weight of Ag and a carbon material is composed of two layers 24a and 24b containing the carbon material and Ag. ) or, as illustrated in FIG. 2, it may be disposed between the solid electrolyte adjacent layer 24b and the solid electrolyte 30 among the two layers.
- the layer 24c containing 0 to 5% by weight of Ag and a carbon material is, as illustrated in FIG. 2, the solid electrolyte adjacent layer 24b and the solid electrolyte adjacent layer 24b of the two layers. It may be desirable to place it between the electrolytes 30.
- the layer 24c containing 0 to 5% by weight of Ag and a carbon material may have a thickness of 1 ⁇ m to 30 ⁇ m.
- the negative electrode active material layer of the present invention contains 80 to 100% by weight and 90 to 100% by weight of Ag based on 100% by weight of the total negative electrode active material layer. %, or may further include a layer comprising 95 to 100% by weight.
- the layer may further include 0 to 20% by weight, 0 to 10% by weight, or 0 to 5% by weight of carbon material.
- the layer may further include a binder, in this case, 80 to 99% by weight of Ag, 0 to 19% by weight of carbon material, and 1 to 10% by weight of binder, and 90 to 99% by weight of Ag. , 0 to 9% by weight of carbon material, and 1 to 10% by weight of binder, and may also include 95 to 99% by weight of Ag, 0 to 4% by weight of carbon material, and 1 to 10% by weight of binder. there is.
- the layer containing 80 to 100% by weight of Ag may be disposed between the negative electrode current collector and a layer adjacent to the negative electrode current collector among the two layers.
- the layer containing 80 to 100% by weight of Ag may have a thickness of 1 ⁇ m to 30 ⁇ m.
- the two or more layers may include one layer containing carbon material and Ag and one layer containing 0 to 5% by weight of Ag and carbon material.
- one layer containing the carbon material and Ag may be relatively located on the current collector side, and one layer including 0 to 5% by weight of Ag and the carbon material may be relatively located on the solid electrolyte side.
- one layer containing 0 to 5% by weight of Ag and carbon material is the same as described above.
- the carbon material particles included in one or more layers in the negative electrode active material layer may be, for example, amorphous carbon material particles.
- carbon material particles are not limited to amorphous particles.
- Specific examples of the amorphous carbon material include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or a combination thereof.
- the size of the pores may be 1 nm or less, preferably 0.5 nm or less. However, it may be more preferable that the amorphous carbon material particles do not contain pores. This is because, when the amorphous carbon material particles contain pores, lithium is precipitated inside the pores, and this lithium may be inactivated, and the amount of lithium thus inactivated may increase as charging and discharging are repeated. Because.
- the pore size of the amorphous carbon material particles can be measured, for example, through a nitrogen adsorption experiment or through a transmission electron microscope.
- the carbon material particles may be carbon material particles containing 3 to 10 at% oxygen.
- oxygen is included in the above-mentioned range, the surface roughness of the negative electrode active material layer can be significantly improved, which is desirable because the driving characteristics of the battery are also improved.
- the oxygen may exist in a form included in a functional group bonded to the carbon material particle.
- the functional group may include one or more selected from the group consisting of a carboxyl group, a hydroxy group, an ether group, an ester group, an aldehyde group, a carbonyl group, and an amide group.
- the carbon material particles containing 3 to 10 at% oxygen can be produced, for example, by oxidizing the carbon material.
- the carbon material can be treated with acid and reacted with stirring at a temperature of 25°C to 60°C to introduce oxygen functional groups to the surface of the carbon material.
- the type of acid is not particularly limited, and any acid that can introduce an oxygen functional group to the surface of the carbon material can be used.
- the acid include sulfuric acid, nitric acid, or mixtures thereof, and an oxidizing agent such as potassium permangate may also be used.
- the content of oxygen contained in the carbon material can be measured using photoelectron spectroscopy (XPS or ESCA). For example, it can be measured using a K-Alpha (Thermo Fisher Scientific) device.
- the oxygen may be present on the surface of the carbon material particles.
- the surface does not mean only the outer surface of the carbon material particle, but includes the surface of the pores if pores exist.
- each negative electrode active material layer may further include one or more particles selected from gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc in addition to Ag particles.
- the carbon material particles may have a particle size (D50) of 10 nm to 100 nm or 20 nm to 60 nm
- the Ag particles and other metal particles may have a particle size (D50) of 20 nm to 100 nm or 20 nm. to 60 nm, or 30 nm to 60 nm may be used.
- one or more layers included in the negative electrode active material layer may contain 2 to 10 at% of oxygen.
- oxygen is included in the above-mentioned range, the surface roughness of the layer is significantly improved, which is desirable because the driving characteristics of the battery can be improved.
- one or more layers containing a carbon material and Ag may further include 65 to 85 at% of carbon and 0.5 to 5 at% of Ag along with the oxygen, and more preferably carbon. It may further include 74 to 85 at% and 0.5 to 3 at% Ag.
- the one or more layers may further include 5 to 25 at% of fluorine (F), and more preferably may further include 10 to 20 at% of fluorine (F).
- Any one of the above layers may further include 0.01 to 1 at% of sulfur (S), and more preferably may further include 0.01 to 0.5 at% of sulfur (S).
- the one or more layers may include 2 to 10 at% oxygen, 65 to 85 at% carbon, 0.5 to 5 at% Ag, and 5 to 25 at% fluorine (F). .
- it may contain 2.5 to 5 at% oxygen, 74 to 85 at% carbon, 0.5 to 3 at% Ag, and 10 to 20 at% fluorine (F).
- sulfur (s) may be further included in addition to the above components.
- the atomic composition ratio can be measured using photoelectron spectroscopy (XPS or ESCA).
- the component ratio can be measured using a Nexsa4 (Thermo Fisher Scientific) device.
- any one or more layers included in the negative electrode active material layer may have the following surface roughness characteristics:
- the overall battery characteristics can be improved, and in particular, the lifespan characteristics can be improved.
- the surface roughness of the negative electrode active material layer exceeds the above range, sufficient contact with the electrolyte layer is not made in the direction of the electrolyte, and it is not conducive to uniform precipitation of lithium in the direction of the negative electrode current collector. This may deteriorate the characteristics of the battery.
- the surface roughness of the negative electrode active material layer can be measured using a microscope device.
- a microscope device For example, it can be measured using a 3D laser confocal microscope (manufactured by KEYENCE).
- Sa (arithmetic mean height of the profile) may be at most 0.3 ⁇ m, 0.2 ⁇ m, 0.1 ⁇ m, 0.08 ⁇ m, or 0.075 ⁇ m, and at least 0.01 ⁇ m, 0.02 ⁇ m, 0.03 ⁇ m, 0.04 ⁇ m. It may be 0.05 ⁇ m or more, 0.06 ⁇ m or more, or 0.07 ⁇ m or more.
- the Sa may be more preferably in the range of 0.01 ⁇ m ⁇ Sa ⁇ 0.1 ⁇ m, but is not limited to these ranges and may be set to a combination of the maximum and minimum values.
- the Sa represents the average value of the absolute value of the height difference between each point with respect to the average plane of the surface.
- Sz maximum height roughness of the profile
- Sz may be at most 5 ⁇ m, 4 ⁇ m, 3 ⁇ m, 2 ⁇ m, or 1.5 ⁇ m, and at least 0.5 ⁇ m, 0.8 ⁇ m, 1 ⁇ m, 1.1 ⁇ m. It may be more than 1.2 ⁇ m, or more than 1.3 ⁇ m.
- the Sz may be more preferably in the range of 0.5 ⁇ m ⁇ Sz ⁇ 1.6 ⁇ m, but is not limited to these ranges and may be set to a combination of the maximum and minimum values.
- the Sz is the maximum height roughness within a single plane and represents the distance between the highest and lowest points within a single plane.
- Spc may be up to 1500 mm -1 or less, 1400 mm -1 or less, 1300 mm -1 or less, 1200 mm -1 or less, 1100 mm -1 or less, or 1000 mm -1 or less, , may be at least 500 mm -1 or more, 600 mm -1 or more, 700 mm -1 or more, 800 mm -1 or more, or 900 mm -1 or more.
- the range of 500 mm -1 ⁇ Spc ⁇ 1100 mm -1 may be more preferable, but is not limited to these ranges and may be set to a combination range of the maximum and minimum values.
- the Spc is roughness based on the number of peaks and is a measure of the steepness of the peak.
- Sdr (interfacial area increase degree) may be at most 0.15 or less, 0.1 or less, 0.05 or less, 0.03 or less, or 0.02 or less, and may be at least 0.005 or more, 0.01 or more, or 0.015 or more. Additionally, the range of 0.005 ⁇ Sa ⁇ 0.03 may be more preferable, but is not limited to this range and may be set to a combination range of the maximum and minimum values.
- the Sdr is the degree of increase in the interface and means the ratio of the area increased compared to the area when the measurement area of the developed area (surface area of the measured shape) is viewed vertically.
- the carbon material particles and Ag particles included in one or more layers of the negative electrode active material layer may be included in the form of a carbon material-metal composite.
- the negative electrode active material layer is formed as a very thin film with a micro thickness, and can be manufactured in a form containing a carbon material-Ag composite in which carbon material particles and Ag particles are combined.
- the conventional carbon material-Ag composite had a problem in that it was difficult for the carbon material particles and Ag particles to be uniformly distributed.
- the conventional carbon material-Ag composite had a problem in that it was very difficult to form a small particle size.
- the particle size of the carbon material-Ag composite is too large compared to the micro-thick thin film, it is difficult to form a negative electrode active material layer with excellent surface roughness, and the driving characteristics of the battery deteriorate accordingly. Therefore, the particle size of the carbon material-Ag composite is reduced. Manufacturing small is very important.
- the present invention provides the effect of dramatically improving the above problems of the prior art.
- the carbon material-Ag composite forms a carbon material-Ag composite with a significantly smaller particle size compared to the case of using a conventional carbon material.
- the carbon material forming the composite contains more than 3 at% of oxygen, mixes well with the metal particles, and has the property of being uniformly distributed with the Ag particles. Therefore, it is possible to manufacture a carbon material-Ag composite with excellent component uniformity. Additionally, for the above reasons, it is possible to manufacture a carbon material-Ag composite with small and uniform particle size.
- the carbon material-Ag composite is a chemical bond between carbon material particles and Ag particles, a van der Waals bond between carbon material particles and Ag particles, and a bond between carbon material particles and Ag particles by a binder. It may be composed of one or more combinations selected from among.
- the chemical bond may be an Ag-O bond between Ag particles and oxygen contained in the carbon material.
- the carbon material particles may have a particle size (D50) of 10 nm to 100 nm or 20 nm to 60 nm
- the Ag particles may have a particle size (D50) of 20 nm to 100 nm, 20 nm to 60 nm, or 30nm to 60nm can be used.
- the particle size (D50) of the carbon material-Ag composite may be 0.1 ⁇ m to 0.5 ⁇ m.
- the upper limit of the particle size may be 0.4 ⁇ m or 0.3 ⁇ m.
- the maximum particle size of the carbon material-Ag composite may be 3 ⁇ m or less, 2 ⁇ m or less, 1.5 ⁇ m or less, and 1 ⁇ m or less.
- the particle size of the carbon material-Ag composite is too large compared to the micro-thick thin film, it is difficult to form a negative active material layer with excellent surface roughness, and the driving characteristics of the battery deteriorate accordingly, so the particle size of the carbon material-Ag composite is reduced. Manufacturing is very important.
- the reason why the driving characteristics of the battery deteriorate is because when the surface roughness of the negative electrode active material layer is large, sufficient contact is not made with the electrolyte layer and it is not conducive to uniform precipitation of lithium on the negative electrode current collector.
- the thickness of the negative electrode active material layer can typically range from 1 ⁇ m to 100 ⁇ m, or 10 ⁇ m to 60 ⁇ m, specifically 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, and 50 ⁇ m. It may be formed to a thickness of ⁇ m or the like.
- the maximum particle size of the carbon material-metal composite is 3 ⁇ m or less, it is preferable because the effect of improving surface roughness can be more reliably obtained. On the other hand, if it exceeds 3 ⁇ m, it may be difficult to obtain excellent surface roughness when forming a thin film. Therefore, the maximum particle size of the carbon material-Ag composite may be 3 ⁇ m or less, 2 ⁇ m or less, 1.5 ⁇ m or less, and 1 ⁇ m or less.
- the particle size of the carbon material-Ag composite can be measured using a particle size analyzer. For example, it can be measured using a Mastersizer 3000 (Malvem panalytical) instrument.
- the positive electrode may include a positive electrode current collector and a positive electrode active material layer.
- the solid electrolyte may be a sulfide-based solid electrolyte.
- Figure 1 is a cross-sectional view schematically showing the schematic configuration of an all-solid lithium ion secondary battery according to an embodiment of the present invention.
- the all-solid lithium ion secondary battery 100 is a so-called lithium ion secondary battery that performs charging and discharging by moving lithium ions between the positive electrode 10 and the negative electrode 20.
- this all-solid lithium ion secondary battery 100 includes a positive electrode 10, a negative electrode 20, and a solid electrolyte layer 30 disposed between the positive electrode 10 and the negative electrode 20. ) is composed of.
- the positive electrode 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14 sequentially disposed toward the negative electrode 20.
- the positive electrode current collector 12 may be plate-shaped or foil-shaped.
- the positive electrode current collector 12 is, for example, one metal selected from indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, and lithium, or an alloy of two or more metals. It can be.
- the positive active material layer 14 can reversibly store and release lithium ions.
- the positive electrode active material layer 14 may include a positive electrode active material and a solid electrolyte.
- the positive electrode active material may be a compound capable of insertion/desorption of lithium.
- Examples of compounds capable of insertion/detachment of lithium include Li a A 1-b B' b D' 2 (in the above formula, 0.90 ⁇ a ⁇ 1.8 and 0 ⁇ b ⁇ 0.5); Li a E 1 - b B' b O 2-c D' c (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); LiE 2-b B' b O 4-c D' c (in the above formula, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a Ni 1-bc Co b B' c D' ⁇ (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05, 0 ⁇ 2); Li a Ni 1-bc Co b B' c O 2- ⁇ F' ⁇ (in the above formula, 0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05, 0 ⁇ 2)
- A is Ni, Co, Mn, or a combination thereof
- B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof
- D' is O, F, S, P, or a combination thereof
- E is Co, Mn, or a combination thereof
- F' is F, S, P, or a combination thereof
- G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof
- Q is Ti, Mo, Mn, or a combination thereof
- I' is Cr, V, Fe, Sc, Y, or a combination thereof
- J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.
- the positive electrode active material examples include lithium cobaltate (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobaltate, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), and lithium nickel cobalt manganate (hereinafter referred to as NCM). ), lithium salts such as lithium manganate and lithium iron phosphate, and lithium sulfide.
- LCO lithium cobaltate
- NCA lithium nickel oxide
- NCM lithium nickel cobalt aluminum oxide
- NCM lithium nickel cobalt manganate
- the positive electrode active material layer 14 may contain only one type selected from these compounds as the positive electrode active material, or may contain two or more types.
- the positive electrode active material may include a lithium salt of a transition metal oxide having a layered halite-type structure among the lithium salts described above.
- the “layered rock salt structure” is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in the direction of the cubic rock salt structure, and as a result, each atomic layer forms a two-dimensional plane.
- “cubic rock salt type structure” means a sodium chloride type structure, which is a type of crystal structure.
- the “cubic rock salt structure” refers to a structure in which face-centered cubic lattices formed of cations and anions are offset from each other by 1/2 of the edges of the unit lattice.
- the positive electrode active material layer 14 may include a lithium salt of a ternary transition metal oxide having such a layered rock salt-type structure as a positive electrode active material, thereby improving the energy density and thermal stability of the all-solid-state lithium ion secondary battery 100.
- examples of the shape of the positive electrode active material include particle shapes such as spherical shape and elliptical sphere shape.
- the particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to the positive electrode active material of a typical all-solid lithium ion secondary battery.
- the content of the positive electrode active material in the positive electrode active material layer 14 is not particularly limited, and can be applied as long as it is within the range applicable to the positive electrode of a typical all-solid lithium ion secondary battery.
- a compound having a coating layer on the surface of the above compound may be used, or a mixture of the above compound and a compound having a coating layer may be used.
- This coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide of the coating element, oxycarbonate of the coating element, or hydroxycarbonate of the coating element.
- the compounds that make up these coating layers may be amorphous or crystalline.
- Coating elements included in the coating layer include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof.
- any coating method may be used as long as the above compounds can be coated with these elements in a manner that does not adversely affect the physical properties of the positive electrode active material (e.g., spray coating, dipping method, etc.). Since this is well-understood by people working in this field, detailed explanation will be omitted.
- the coating layer include Li 2 O-ZrO 2 and the like.
- the solid electrolyte included in the positive electrode active material layer 14 may be the same as or different from the solid electrolyte included in the solid electrolyte layer 30, which will be described later.
- the positive electrode active material layer 14 is formed by appropriately mixing not only the positive electrode active material and solid electrolyte described above, but also additives such as, for example, a conductive agent, binder, filler, dispersant, or ion conductive auxiliary agent. It may be.
- Examples of the conductive agent include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or metal powder.
- examples of the binder (binder) include styrenebutadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene.
- SBR styrenebutadiene rubber
- known materials commonly used in electrodes of all-solid-state lithium ion secondary batteries can be used as the filler, dispersant, or ion conductive auxiliary agent.
- the negative electrode 20 may include a negative electrode current collector 22 and a negative electrode active material layer 24 sequentially disposed toward the positive electrode 10 .
- the negative electrode current collector 22 may be plate-shaped or foil-shaped.
- the negative electrode current collector 22 may include a material that does not react with lithium, that is, does not form any alloy or compound with lithium.
- Materials constituting the negative electrode current collector 22 include, for example, copper, stainless steel, titanium, iron, cobalt, and nickel.
- the negative electrode current collector 22 may be composed of one type of these metals, or may be composed of an alloy or clad material of two or more types of metals.
- the negative electrode active material layer 24 may include one or two or more types of negative electrode active materials capable of forming an alloy or compound with lithium. In the initial state or the state after complete discharge, lithium may not be contained in the negative electrode current collector 22, the negative electrode active material layer 24, or between the negative electrode active material layer 24 and the solid electrolyte layer 30. As will be described later, when the all-solid lithium ion secondary battery 100 according to one embodiment is overcharged, the negative electrode active material contained in the negative electrode active material layer 24 and the lithium ions moving from the positive electrode 10 form an alloy or compound. And as shown in FIG. 4, a metal layer 26 containing lithium as a main component may be formed (precipitated) on the cathode 20.
- the metal layer 26 may be deposited and disposed between the negative electrode current collector 22 and the negative electrode active material layer 24, inside the negative electrode active material layer 24, or both. Between the negative electrode current collector 22 and the negative electrode active material layer 24, the metal layer 26 mainly containing lithium may be disposed closer to the negative electrode current collector layer 22 than the negative electrode active material layer 24. .
- the anode active material layer 24 may include Ag as an essential anode active material. Therefore, the metal layer 26 formed during overcharging may include a Li(Ag) alloy including a ⁇ 1 phase in which Ag is dissolved in lithium, a ⁇ Li phase, or a combination thereof. Therefore, during discharge, only Li is dissolved in the Li(Ag) alloy constituting the metal layer 26, and the dissolved Ag remains, thereby suppressing the generation of voids. In this case, the content of Ag in the precipitated Li-Ag solid solution may be 60% by weight or less. Within this range, the decrease in average discharge potential due to the influence of Ag can be effectively suppressed.
- the content of Ag in the precipitated Li-Ag solid solution may be 20% by weight or more, for example, 40% by weight or more.
- Ag does not necessarily have to exist uniformly in the negative electrode active material layer 24, but may be localized on the negative electrode current collector 22 side of the negative electrode active material layer 24.
- lithium ions react with the Ag localization layer in the negative electrode active material layer 24 that has reached the vicinity of the negative electrode current collector 22, thereby forming a Li(Ag) alloy into the metal layer 26.
- the negative electrode active material layer 24 contains 10% by weight or more of Ag, for example, 20% by weight or more, based on 100% by weight of the total negative electrode active material contained in the negative electrode active material layer, in the initial state without charging or discharging. can do.
- the upper limit of the Ag content in the negative electrode active material included in the negative electrode active material layer 24 may be 100% by weight.
- the Ag content may be 80% by weight or less, for example, 50% by weight or less.
- the Ag content (% by weight) in the negative electrode active material layer 24 can be measured, for example, as follows. That is, after discharging the all-solid-state lithium ion secondary battery 100, it is dismantled, and the negative electrode active material layer 24 is recovered from the surface of the negative electrode 20. And the Ag content in the recovered product can be determined using EDX, XRF, or ICP. Also, for example, the Ag content can be known from SEM-EDS analysis in the cross-sectional direction.
- the Ag content per unit area in the negative electrode active material layer 24 when viewed from the stacking direction of the negative electrode 20 is too small, the Ag remaining during discharge will also decrease, making it impossible to suppress the generation of voids. There are concerns. Therefore, the Ag content per unit area in the negative electrode active material layer 24 may be 0.05 mg/cm 2 or more, for example, 0.10 mg/cm 2 or more.
- the Ag content per unit area may be 5.0 mg/cm 2 or less, for example, 2.0 mg/cm 2 or less.
- the Ag content per unit area of the negative electrode active material layer 24 can be measured, for example, as follows. That is, the all-solid lithium ion secondary battery 100 is dismantled after discharging, and the Ag content can be known from composition analysis by SEM-EDS on the surface or cross-sectional direction of the negative electrode 20. It is not limited to this, and the Ag content can also be known through XPS and ICP.
- Ag included in the negative electrode active material layer 24 may be in the form of particles or a film.
- the average particle diameter (d50) (diameter length or average diameter) of Ag may be 20 nm to 1 ⁇ m, but is not limited thereto.
- the negative electrode active material layer 24 is any negative electrode active material other than Ag, and may further include, for example, one or more types selected from amorphous carbon, Au, Pt, Pd, Si, Al, Bi, Sn, In, and Zn. You can.
- Amorphous carbon may be preferably used as the carbon material included in the negative electrode active material layer 24.
- Specific examples of the amorphous carbon include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or a combination thereof.
- the total amount of negative electrode active materials other than Ag may be 50% by weight or more, for example, 70% by weight or more.
- the content of negative electrode active materials other than Ag can be measured in the same manner as the Ag content.
- the negative electrode active material layer 24 may further include a binder.
- a binder By including a binder, the negative electrode active material layer 24 can be stabilized on the negative electrode current collector 22.
- materials constituting the binder (binder) include resin materials such as styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene.
- SBR styrene-butadiene rubber
- the binder (binder) may be composed of one or more types selected from these resin materials.
- the negative electrode active material layer 24 may be appropriately mixed with additives used in conventional all-solid-state lithium ion secondary batteries, such as fillers, dispersants, and ion conductive agents. Specific examples of the additives are the same as those described for the above-mentioned positive electrode.
- the total thickness of the negative electrode active material layer 24 is not particularly limited, but may be 1 ⁇ m to 100 ⁇ m, or 10 ⁇ m to 60 ⁇ m. If the thickness of the negative electrode active material layer 24 is less than 1 ⁇ m, the performance of the all-solid-state secondary battery may not be sufficiently improved. When the thickness of the negative electrode active material layer 24 exceeds 100 ⁇ m, the resistance of the negative electrode active material layer 24 is high, and as a result, the performance of the all-solid-state secondary battery may not be sufficiently improved. By using the above-described binder, the thickness of the negative electrode active material layer 24 can be easily secured at an appropriate level.
- a film containing a material capable of forming an alloy or compound with lithium may be further included on the negative electrode current collector 22, and the film may be disposed between the negative electrode current collector 22 and the negative electrode active material layer.
- the negative electrode current collector 22 does not react with lithium metal, it can make it difficult to deposit a smooth lithium metal layer on the top.
- the film can also be used as a wetting layer that allows lithium metal to precipitate evenly on the top of the negative electrode current collector 22.
- Materials capable of forming an alloy with lithium metal used in the film may include silicon, magnesium, aluminum, lead, silver, tin, or a combination thereof.
- Materials capable of forming a compound with lithium metal used in the film may include carbon, titanium sulfide, iron sulfide, or a combination thereof.
- the content of the material used in the membrane may be small as long as it does not affect the electrochemical properties of the electrode or/and the redox potential of the electrode.
- the film can be applied evenly on the negative electrode current collector 22 to prevent cracking during the charging cycle of the all-solid-state lithium ion secondary battery 100.
- the film may be applied using methods such as evaporation or sputtering, physical vapor deposition, chemical vapor deposition, or plating methods.
- the thickness of the film may be 1 nm to 500 nm.
- the thickness of the film may be, for example, 2 nm to 400 nm.
- the thickness of the film may be, for example, 3 nm to 300 nm.
- the thickness of the film may be, for example, 4 nm to 200 nm.
- the thickness of the film may be, for example, 5 nm to 100 nm.
- the solid electrolyte layer 30 is disposed between the positive electrode 10 and the negative electrode 20 (for example, between the positive electrode active material layer 14 and the negative electrode active material layer 24).
- the solid electrolyte layer 30 includes a solid electrolyte capable of moving ions.
- the solid electrolyte layer 30 may include a sulfide-based solid electrolyte.
- the sulfide-based solid electrolyte is Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiX (X is a halogen element), Li 2 SP 2 S 5 -Li 2 O, Li 2 SP 2 S 5 -Li 2 O- LiI, Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m and n are positive numbers, Z is one of Ge, Zn or Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li p MO q (p
- the sulfide-based solid electrolyte may include a solid electrolyte represented by the following formula (1):
- x, y, z, and w are independently from 0 to 6;
- M' is one or more of As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta;
- A is one or more of F, Cl, Br, or I.
- one containing sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the sulfide solid electrolyte materials can be used.
- one containing Li 2 SP 2 S 5 may be used.
- the solid electrolyte may be in an amorphous state or a crystalline state. Additionally, it may be in a mixed state of amorphous and crystalline.
- the solid electrolyte layer 30 may further include a binder.
- the binder (binder) material include resins such as styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polyacrylic acid.
- SBR styrene-butadiene rubber
- the binder material may be the same as or different from the material constituting the binder (binder) in the positive electrode active material layer 14 and the negative electrode active material layer 24.
- the initial charge capacity of the positive electrode active material layer 14 is excessive compared to the initial charge capacity of the negative electrode active material layer 24.
- the all-solid lithium ion secondary battery 100 can be used by charging (i.e., overcharging) exceeding the initial charging capacity of the negative electrode active material layer 24.
- charging i.e., overcharging
- lithium may be stored in the negative electrode active material layer 24. That is, the negative electrode active material can form an alloy or compound with lithium ions that have migrated from the positive electrode 10.
- charging exceeds the initial charge capacity of the negative electrode active material layer 24, as shown in FIG.
- Lithium may precipitate, and the metal layer 26 may be formed by this lithium.
- the metal layer 26 may be mainly composed of lithium in which Ag is dissolved (i.e., Ag-Li solid solution).
- This phenomenon may consist of a negative electrode active material, for example, a material that forms an alloy or compound with lithium.
- the lithium in the negative electrode active material layer 24 and the metal layer 26 is ionized and can move toward the positive electrode 10 while leaving the dissolved Ag remaining. Therefore, lithium can be used as a negative electrode active material in the all-solid lithium ion secondary battery 100.
- the negative electrode active material layer 24 coats the metal layer 26, it functions as a protective layer for the metal layer 26 and can suppress precipitation and growth of dendritic metal lithium.
- the all-solid lithium ion secondary battery 100 has the ratio of the initial charge capacity of the positive electrode active material layer 14 to the initial charge capacity of the negative electrode active material layer 24, that is, the initial charge capacity ratio b/a, as follows: It is desirable to satisfy equation (100).
- a is the initial charge capacity (mAh) of the positive electrode active material layer 14
- b is the initial charge capacity (mAh) of the negative electrode active material layer 24
- the initial charge capacity ratio is 0.01 or less, there is a risk that the characteristics of the all-solid-state lithium ion secondary battery 100 may deteriorate.
- the negative electrode active material layer 24 does not function sufficiently as a protective layer.
- the capacity ratio may be 0.01 or less.
- the initial charge capacity ratio may be 0.01 or more.
- the initial charge capacity ratio is more than 0.5, there is a risk that the battery capacity will decrease because the amount of lithium precipitation from the negative electrode decreases. Therefore, the initial charge capacity ratio may be less than 0.5.
- the all-solid lithium ion secondary battery 100 of the present invention is an all-solid lithium ion secondary battery 100 that includes a positive electrode 10, a solid electrolyte layer 30, and a negative electrode 20 in this order.
- the negative electrode 20 includes a negative electrode current collector 22 and a negative electrode active material layer 24, and the negative electrode active material layer 24 includes carbon material and Ag and includes two or more layers.
- the negative electrode current collector 22 may include Ni foil, Ni-coated Cu foil, stainless steel foil, or a combination thereof. The discharge capacity of this negative electrode current collector 22 can be further improved.
- the all-solid lithium ion secondary battery 100 can be obtained by manufacturing the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30, and then stacking each of the above layers.
- the anode manufacturing process is explained with an example as follows. First, the materials constituting the positive electrode active material layer 14 (positive electrode active material, binder, etc.) are added to a non-polar solvent to produce a slurry (or paste). Next, the obtained slurry is applied onto the prepared positive electrode current collector 12. This is dried to obtain a laminate. Next, the obtained laminate is pressurized using, for example, hydrostatic pressure to obtain the anode 10. Additionally, the pressurizing process is omitted.
- the cathode manufacturing process is explained with an example as follows. First, the materials constituting the negative electrode active material layer 24 (negative electrode active material containing Ag, binder, etc.) are added to a polar solvent or non-polar solvent to prepare a slurry (may be a paste). Next, the obtained slurry is applied on the prepared negative electrode current collector 22 to form a first layer of negative electrode active material. Next, a slurry (which may be a paste) is prepared by mixing the first layer with different amounts of Ag. Next, the obtained slurry is applied to the upper surface of the second layer and dried to obtain a laminate.
- a slurry may be a paste
- the additional layers can be laminated in the same manner as above.
- the cathode 20 is manufactured by pressurizing the obtained laminate using, for example, hydrostatic pressure. Additionally, the pressurizing process may be omitted. Additionally, the method of applying the slurry to the negative electrode current collector 22 is not particularly limited, and includes, for example, screen printing, metal mask printing, electrostatic coating, dip coating, spray coating, roll coating, and doctor blade method. , gravure coating method, etc.
- the solid electrolyte layer 30 can be manufactured using, for example, a solid electrolyte containing a sulfide-based solid electrolyte material.
- starting raw materials e.g., Li2S, P2S5, etc.
- a sulfide-based solid electrolyte material can be produced by mixing a predetermined amount of starting materials, forming pellets, reacting at a predetermined reaction temperature in a vacuum, and then quenching.
- the reaction temperature of the mixture of Li 2 S and P 2 S 5 may be 400°C to 1000°C, for example, 800°C to 900°C.
- the reaction time may be 0.1 hour to 12 hours, for example, 1 hour to 12 hours.
- the quenching temperature of the reactant may be 10°C or lower, for example, 0°C or lower, and the quenching rate may generally be 1°C/sec to 10000°C/sec, for example, 1°C/sec to 1000°C/sec.
- a sulfide-based solid electrolyte material can be produced by stirring and reacting the starting materials using a ball mill or the like.
- the stirring speed and stirring time of the mechanical milling method are not particularly limited, but the faster the stirring speed, the faster the production rate of the sulfide-based solid electrolyte material, and the longer the stirring time, the higher the conversion rate of raw materials to the sulfide-based solid electrolyte material. It can be raised.
- the obtained mixed raw material (sulfide-based solid electrolyte material) is heat-treated at a predetermined temperature and then pulverized to produce a particle-shaped solid electrolyte.
- a solid electrolyte When a solid electrolyte has a glass transition point, it may change from amorphous to crystalline through heat treatment.
- the solid electrolyte obtained by the above method can be used to form a film using known film forming methods such as the aerosol position method, cold spray method, and sputtering method, thereby producing the solid electrolyte layer 30. Additionally, the solid electrolyte layer 30 can be manufactured by pressing solid electrolyte particles. Additionally, the solid electrolyte layer 30 can be manufactured by mixing a solid electrolyte, a solvent, and a binder, applying, drying, and pressing.
- An all-solid lithium ion secondary battery 100 can be obtained by placing a solid electrolyte layer 30 between the anode 10 and the cathode 20 and pressurizing it using, for example, hydrostatic pressure. there is.
- the all-solid-state lithium ion secondary battery 100 of the present invention does not need to apply high external pressure using an end plate, etc., and when used, the pressure applied to the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30 Even if the external pressure is less than 1 MPa, improved discharge capacity can be provided.
- a method of charging the all-solid lithium ion secondary battery 100 may be to charge the all-solid lithium ion secondary battery 100 beyond the charging capacity of the negative electrode active material layer 24 (i.e., overcharge).
- lithium may be stored in the negative electrode active material layer 24.
- lithium is precipitated on the back side of the negative electrode active material layer 24, that is, between the negative electrode current collector 22 and the negative electrode active material layer 24, as shown in FIG.
- This lithium can form a metal layer 26 that did not exist during manufacture.
- lithium in the negative electrode active material layer 24 and the metal layer 26 is ionized and may move toward the positive electrode 10. Therefore, in the all-solid lithium ion secondary battery 100 of the present invention, lithium can be used as a negative electrode active material.
- the negative electrode active material layer 24 coats the metal layer 26, it functions as a protective layer for the metal layer 26 and can suppress precipitation and growth of dendritic metal lithium. In this way, short circuiting and capacity reduction of the all-solid-state lithium ion secondary battery 100 can be suppressed, and further, the characteristics of the all-solid-state lithium ion secondary battery 100 can be improved. Additionally, according to one embodiment, since the metal layer 26 is not formed in advance, the manufacturing cost of the all-solid-state lithium ion secondary battery 100 can be reduced.
- the metal layer 26 is not limited to being formed between the negative electrode current collector 22 and the negative electrode active material layer 24 as shown in FIG. 4, and may be formed inside the negative electrode active material layer 24. Additionally, the metal layer 26 may be formed both between the negative electrode current collector 22 and the negative electrode active material layer 24 and inside the negative electrode active material layer 24.
- the all-solid lithium ion secondary battery 100 of the present invention is a unit cell having a positive electrode/separator/negative electrode structure, a bicell having a positive electrode/separator/negative electrode/separator/positive electrode structure, or a stack in which the structure of the unit cells is repeated. It can be manufactured in the structure of a battery.
- the shape of the all-solid-state lithium ion secondary battery 100 of the present invention is not particularly limited, and examples include coin shape, button shape, sheet shape, stacked shape, cylindrical shape, flat shape, and horn shape. It can also be applied to large batteries used in electric vehicles, etc.
- the all-solid-state lithium ion secondary battery 100 can also be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). Additionally, it can be used in fields that require large amounts of power storage. For example, it can be used in electric bicycles or power tools.
- An amorphous carbon material containing 6 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 2 g of Ag with a particle size (D50) of 40 nm to 60 nm, 9.33 g of PVdF binder (solid content 6%), and 7.67 g of NMP solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, an additional 5 g of NMP solution was added and mixed five times for 3 minutes each at 2000 rpm to prepare a negative electrode active material slurry.
- the slurry was coated on SUS foil to a thickness of 60 ⁇ m and dried to prepare a negative electrode.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
- the first negative electrode active material slurry was coated to a thickness of 30 ⁇ m on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 30 ⁇ m on the upper surface of the first negative electrode active material layer formed by the coating and dried.
- a cathode was prepared.
- the first negative electrode active material slurry was coated to a thickness of 30 ⁇ m on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 30 ⁇ m on the upper surface of the first negative electrode active material layer formed by the coating and dried.
- a cathode was prepared.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
- the first negative electrode active material slurry was coated on a SUS foil to a thickness of 20 ⁇ m and dried, and then the second negative electrode active material slurry was coated at a thickness of 20 ⁇ m on the upper surface of the first negative electrode active material layer formed by the coating and dried. .
- the third negative electrode active material slurry was coated to a thickness of 20 ⁇ m on the upper surface of the second negative electrode active material layer formed by the coating and dried to prepare a negative electrode.
- Example 1 the first negative electrode active material slurry was coated on a SUS foil to a thickness of 40 ⁇ m (Example 1: 30 ⁇ m) and dried, and then the second negative electrode active material was applied to the upper surface of the first negative electrode active material layer formed by the coating.
- a negative electrode was manufactured in the same manner as in Example 1, except that the slurry was coated to a thickness of 20 ⁇ m (Example 1: 30 ⁇ m) and dried.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
- 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
- the third negative electrode active material slurry was coated to a thickness of 10 ⁇ m on the SUS foil and dried, and then the first negative electrode active material slurry was coated to a thickness of 20 ⁇ m on the upper surface of the third coating layer and dried, and then the first negative electrode active material slurry formed by the coating was coated and dried.
- the second negative electrode active material slurry was coated to a thickness of 20 ⁇ m on the upper surface of the negative electrode active material layer and dried to prepare a negative electrode.
- 1.5g was placed in a Thinky mixer container and mixed 12 times at 2000rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
- the first negative electrode active material slurry was coated to a thickness of 20 ⁇ m on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 40 ⁇ m on the upper surface of the first negative electrode active material layer formed by the coating and dried.
- a cathode was prepared.
- Example 7 As the positive electrode, a positive electrode in which the positive electrode active material was loaded at 5 mAh/cm 2 on the current collector was used, and as the negative electrode, the positive electrode prepared in Example 6 and Comparative Example 1 was used.
- the pouch-type monocell of Example 7 and Comparative Example 2 was manufactured using a negative electrode and a sulfide-based all-solid electrolyte as the electrolyte.
- Example 7 The pouch-type monocell of Example 7 and Comparative Example 2 was driven under the following charge/discharge conditions at an operating voltage range of 4.25V-3.0V and a drive temperature of 60°C to evaluate cycle characteristics, and the results are shown in FIG. 6.
- Figure 6 shows an SEM image of the cathode of Example 6.
- the negative electrode of Example 6 has many Ag particles disposed in the active material layer close to the current collector, and the battery of Example 7 includes a negative electrode with this structure, so that the cycle characteristics are improved. It appears to have improved.
- Example 2 The same as the first anode active material slurry of Example 1, except that carbon black with an oxygen content of 2.6 at% was used instead of carbon black with an oxygen content of 5.2 at%. A portion of the carbon material-metal composite contained in the negative electrode active material slurry of Comparative Example 2 prepared by the method was taken and diluted in NMP solution to prepare an analysis sample.
- Particle size analysis was performed using a particle size analyzer model name Mastersizer 3000 (Malvem panalytical). Specifically, carbon material-metal composite analysis sample 1 (Example 1, including carbon black with an oxygen content of 5.2 at%) and carbon material-metal composite analysis sample 2 (including carbon black with an oxygen content of 2.6 at%) prepared in (1) above. ) was placed into the sample inlet of the device to be 10-15% of the laser obscuration, and the measurement was performed.
- Mastersizer 3000 Malvem panalytical
- the analysis device is capable of analyzing particle sizes ranging from 0.01 ⁇ m to 3500 ⁇ m, and is a particle size analyzer suitable for wet and dry dispersion types through laser diffraction.
- the particle size of the carbon material-metal composite containing carbon black with an oxygen content of 5.2 at% is significantly smaller than that of the carbon material-metal composite containing carbon black with an oxygen content of 2.6 at%. Able to know.
- the maximum particle size of the carbon material-metal composite containing carbon black with an oxygen content of 5.2 at% is 1 ⁇ m or less
- the carbon material containing carbon black with an oxygen content of 2.6 at% is 1 ⁇ m or less. -You can see that it is significantly smaller compared to the particle size of the metal composite.
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Abstract
The present invention provides an all-solid-state lithium-ion secondary battery comprising a positive electrode, a negative electrode, and a solid electrolyte interposed between the positive electrode and the negative electrode, wherein the negative electrode comprises a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer comprises a carbon material and Ag and comprises two or more layers.
Description
본 출원은 2022년 11월 2일자 한국 특허 출원 제10-2022-0144772호 및 2023년 10월 31일자 한국 특허 출원 제10-2023-0148468호에 기초한 우선권의 이익을 주장하며, 해당 한국 특허 출원의 문헌에 개시된 모든 내용은 본 명세서의 일부로서 포함한다.This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0144772 dated November 2, 2022 and Korean Patent Application No. 10-2023-0148468 dated October 31, 2023, and the Korean Patent Application No. All content disclosed in the literature is incorporated as part of this specification.
본 발명은 전고체 리튬이온 이차전지에 관한 것이다.The present invention relates to an all-solid lithium ion secondary battery.
최근 전해질로서 고체 전해질을 이용한 전고체 이차전지가 주목받고 있다. 이러한 전고체 이차전지의 에너지 밀도를 향상시키기 위해 음극 활물질로 리튬을 사용하는 것이 제안되어 있다. 리튬의 용량 밀도(단위중량당 용량)는 음극 활물질로서 일반적으로 사용되는 흑연의 용량밀도의 10배 정도이다. 따라서 음극 활물질로 리튬을 사용하는 경우, 전고체 이차전지를 박형화하면서도 출력을 높이는 것이 가능하다.Recently, all-solid-state secondary batteries using solid electrolytes as electrolytes have been attracting attention. To improve the energy density of these all-solid-state secondary batteries, it has been proposed to use lithium as a negative electrode active material. The capacity density (capacity per unit weight) of lithium is about 10 times that of graphite, which is commonly used as a negative electrode active material. Therefore, when using lithium as a negative electrode active material, it is possible to increase the output while reducing the thickness of the all-solid-state secondary battery.
전고체 리튬이온 이차전지로서, 예를 들어 리튬과 합금을 형성하는 금속으로 형성된 금속층을 음극 활물질층으로 설치하고, 음극 활물질층 상에 비정질 탄소로 이루어진 계면층을 구비한 것이 알려져 있다. 이런 종류의 전고체 리튬이온 이차전지는 충전시에는 비정질 탄소 계면층과 음극 활물질층 사이에 금속 리튬이 석출되고, 방전시에는 해당 금속리튬이 이온화하여 양극 쪽으로 이동한다.As an all-solid lithium ion secondary battery, for example, it is known that a metal layer formed of a metal that forms an alloy with lithium is provided as a negative electrode active material layer, and an interface layer made of amorphous carbon is provided on the negative electrode active material layer. In this type of all-solid-state lithium-ion secondary battery, metallic lithium precipitates between the amorphous carbon interface layer and the negative electrode active material layer when charging, and when discharging, the metallic lithium is ionized and moves toward the positive electrode.
그런데, 상술한 바와 같은 전고체 리튬이온 이차전지는 충방전을 반복하면 비정질 탄소 계면층과 음극 활물질층 사이에 석출된 금속리튬이 이온화하여 용해됨으로써 공극이 생겨 전지로 사용할 수 없게 될 수 있다. 따라서 이런 종류의 전고체 리튬이온 이차전지를 실제적으로 사용하는 경우에는 충방전에 의해 공극이 생기는 것을 방지하기 위해 엔드 플레이트(end plate) 등을 양극 집전체측 및 음극 집전체측의 양측에서 끼워넣어 높은 외압을 인가할 필요가 있다. 그러나 외압을 인가하는 엔드 플레이트 등의 존재는 전고체 리튬이온 이차전지의 박형화의 장벽이 될 수 있다. However, when the all-solid lithium ion secondary battery as described above is repeatedly charged and discharged, the metallic lithium precipitated between the amorphous carbon interface layer and the negative electrode active material layer is ionized and dissolved, creating a void, which may make it unusable as a battery. Therefore, when this type of all-solid-state lithium-ion secondary battery is actually used, end plates, etc. must be inserted from both sides of the positive and negative current collector sides to prevent voids from forming during charging and discharging. It is necessary to apply high external pressure. However, the presence of an end plate that applies external pressure can be a barrier to thinning of the all-solid-state lithium-ion secondary battery.
따라서 높은 외압을 인가할 필요가 없고, 방전용량이 뛰어난 전고체 리튬이온 이차전지의 개발이 활발히 이루어지고 있다. Therefore, the development of all-solid-state lithium-ion secondary batteries that do not require high external pressure and have excellent discharge capacity is being actively developed.
[선행기술문헌][Prior art literature]
[특허문헌][Patent Document]
대한민국 공개특허 제10-2015-0064697호Republic of Korea Patent Publication No. 10-2015-0064697
본 발명은, 종래 기술의 상기와 같은 문제를 해결하기 위하여 안출된 것으로서, The present invention was devised to solve the above problems of the prior art,
높은 외압을 인가할 필요가 없고, 덴드라이트 형성이 억제되며, 우수한 방전용량 및 수명 특성을 갖는 전고체 리튬이온 이차전지를 제공하는 것을 목적으로 한다.The purpose is to provide an all-solid lithium ion secondary battery that does not require high external pressure, suppresses dendrite formation, and has excellent discharge capacity and lifespan characteristics.
상기 목적을 달성하기 위하여, 본 발명은 In order to achieve the above object, the present invention
양극, 음극, 및 상기 양극 및 음극 사이에 개재된 고체 전해질을 포함하며, It includes an anode, a cathode, and a solid electrolyte interposed between the anode and the cathode,
상기 음극은 음극 집전체와 음극 활물질층을 포함하며,The negative electrode includes a negative electrode current collector and a negative electrode active material layer,
상기 음극 활물질층은 탄소재와 Ag를 포함하며, 2개 이상의 층을 포함하는 전고체 리튬이온 이차전지를 제공한다.The negative electrode active material layer includes carbon material and Ag, and provides an all-solid lithium ion secondary battery including two or more layers.
본 발명의 전고체 리튬이온 이차전지는 높은 외압을 인가할 필요가 없고, 덴드라이트 형성이 억제되며, 우수한 방전용량 및 수명 특성을 제공한다.The all-solid lithium ion secondary battery of the present invention does not need to apply high external pressure, suppresses dendrite formation, and provides excellent discharge capacity and lifespan characteristics.
도 1 내지 4는 본 발명의 전고체 리튬이온 이차전지의 구조를 모식적으로 나타낸 단면도이며,1 to 4 are cross-sectional views schematically showing the structure of the all-solid lithium ion secondary battery of the present invention;
도 5는 본 발명의 실시예 7과 비교예 2의 전고체 리튬이온 이차전지의 사이클 특성을 측정한 결과를 나타낸 그래프이며, Figure 5 is a graph showing the results of measuring the cycle characteristics of the all-solid lithium ion secondary battery of Example 7 and Comparative Example 2 of the present invention;
도 6은 본 발명의 실시예 6의 음극에 대한 SEM 이미지를 나타낸다.Figure 6 shows an SEM image of the cathode of Example 6 of the present invention.
도 7은 본 발명의 탄소재-금속 복합체의 입도 분포를 나타낸 그래프이다.Figure 7 is a graph showing the particle size distribution of the carbon material-metal composite of the present invention.
이하, 본 발명에 대한 이해를 돕기 위해 본 발명을 더욱 상세하게 설명한다.Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention.
본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이거나 사전적인 의미로 한정해서 해석되어서는 아니되며, 발명자는 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다. 또한, 본 명세서에서 사용되는 용어는 단지 예시적인 실시예들을 설명하기 위해 사용된 것으로, 본 발명을 한정하려는 의도는 아니다. 단수의 표현은 문맥상 명백하게 다르게 뜻하지 않는 한, 복수의 표현을 포함한다.Terms or words used in this specification and claims should not be construed as limited to their common or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the present invention based on the principle that it is. Additionally, the terminology used herein is only used to describe exemplary embodiments and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.
어떤 구성요소가 다른 구성요소에 "연결된다, 구비된다, 또는 설치된다"고 언급된 때에는, 그 다른 구성요소에 직접적으로 연결 또는 설치될 수도 있지만, 중간에 다른 구성요소가 존재할 수도 있다고 이해되어야 한다. 반면에, 어떤 구성요소가 다른 구성요소에 "직접 연결된다 또는 설치된다"라고 언급된 때에는 중간에 다른 구성요소가 존재하지 않는 것으로 이해되어야 한다. 한편, 구성요소들 간의 관계를 설명하는 다른 표현들, 즉 "~상부에"와 "상부에 직접" 또는 "~사이에"와 "바로 ~사이에" 또는 "~에 이웃하는"과 "~에 직접 이웃하는" 등도 마찬가지로 해석되어야 한다.When a component is referred to as “connected, provided, or installed” to another component, it should be understood that it may be directly connected to or installed on the other component, but that other components may exist in between. . On the other hand, when a component is referred to as being “directly connected to or installed” on another component, it should be understood that there are no other components in between. On the other hand, there are other expressions that describe the relationship between components, such as “on top of” and “directly on top of” or “between” and “immediately between” or “neighboring to” and “to” “Direct neighbors” etc. should be interpreted similarly.
본 명세서에서 "조합"이라는 용어는 특별히 반대되는 기재가 없는 한 혼합물, 합금, 반응 생성물 등을 포함한다. 본 명세서에서 "제1", "제2" 등의 용어는 순서, 양 또는 중요성을 나타내지 않고, 하나의 요소를 다른 요소와 구별하기 위해 사용된다.As used herein, the term “combination” includes mixtures, alloys, reaction products, etc., unless specifically stated otherwise. In this specification, terms such as “first” and “second” do not indicate order, quantity, or importance, but are used to distinguish one element from another element.
본 발명의 전고체 리튬이온 이차전지(100)는, 도 1에 예시된 바와 같이, 양극(10), 음극(20), 및 상기 양극 및 음극 사이에 개재된 고체 전해질(30)을 포함하며,As illustrated in FIG. 1, the all-solid-state lithium ion secondary battery 100 of the present invention includes a positive electrode 10, a negative electrode 20, and a solid electrolyte 30 interposed between the positive electrode and the negative electrode,
상기 음극은 집전체(22)와 음극 활물질층(24)을 포함하며,The negative electrode includes a current collector 22 and a negative electrode active material layer 24,
상기 음극 활물질층(24)은 탄소재와 Ag를 포함하며, 2개 이상의 층을 포함하는 것을 특징으로 한다. The anode active material layer 24 includes carbon material and Ag, and is characterized by including two or more layers.
본 발명의 일 실시형태에 있어서, 상기 2개 이상의 층은 탄소재와 Ag를 포함하는 2개의 층을 포함하며, 상기 2개의 층은 서로 다른 Ag 함량을 포함하는 특징을 갖는다. In one embodiment of the present invention, the two or more layers include two layers including a carbon material and Ag, and the two layers include different Ag contents.
본 발명의 일 실시형태에 있어서, 상기 탄소재와 Ag를 포함하는 2개의 층 중 음극 집전체(22)에 인접하여 배치되는 층(예: 도 1, 24a)은 고체 전해질(30)에 인접하여 배치되는 층(예: 도 1, 24b)보다 Ag 함량 비율이 더 높은 특징을 가질 수 있다. 이러한 구조의 전고체 전지는 더 우수한 방전용량 및 수명 특성을 제공할 수 있다.In one embodiment of the present invention, of the two layers including the carbon material and Ag, the layer disposed adjacent to the negative electrode current collector 22 (e.g., FIGS. 1 and 24a) is adjacent to the solid electrolyte 30. It may be characterized by a higher Ag content ratio than the disposed layer (e.g., Figure 1, 24b). All-solid-state batteries with this structure can provide better discharge capacity and lifespan characteristics.
구체적으로, 상기 음극 집전체에 인접하여 배치되는 층은 상기 고체 전해질에 인접하여 배치되는 층보다 1.5배 내지 10배, 바람직하게는 2배 내지 8배, 2배 내지 4배, 또는 2배 내지 3배의 Ag를 포함할 수 있다. Specifically, the layer disposed adjacent to the negative electrode current collector is 1.5 to 10 times, preferably 2 to 8 times, 2 to 4 times, or 2 to 3 times larger than the layer disposed adjacent to the solid electrolyte. It may contain double Ag.
상기 음극 집전체에 인접하여 배치되는 층은 음극 활물질층 전체 100 중량%를 기준으로 Ag를 20 내지 80 중량%, 20 내지 60 중량%, 또는 25 내지 55 중량%로 포함할 수 있으며, 음극 활물질층 전체 100 중량%를 기준으로 탄소재를 20 내지지 80 중량% 또는 40 내지 80 중량% 포함할 수 있다.The layer disposed adjacent to the negative electrode current collector may include 20 to 80% by weight, 20 to 60% by weight, or 25 to 55% by weight of Ag based on 100% by weight of the total negative electrode active material layer, and the negative electrode active material layer It may contain 20 to 80% by weight or 40 to 80% by weight of carbon material based on 100% by weight of the total.
또한, 상기 음극 집전체에 인접하여 배치되는 음극 활물질층은 바인더를 더 포함할 수 있으며, 이 경우, Ag 20 내지 75 중량%, 탄소재 20 내지 75 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있으며, 또한, Ag 25 내지 55 중량%, 탄소재 40 내지 73 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있다.In addition, the negative electrode active material layer disposed adjacent to the negative electrode current collector may further include a binder, in this case, 20 to 75% by weight of Ag, 20 to 75% by weight of carbon material, and 1 to 10% by weight of binder. It may also include 25 to 55% by weight of Ag, 40 to 73% by weight of carbon material, and 1 to 10% by weight of binder.
상기 고체 전해질에 인접하여 배치되는 층은 음극 활물질층 전체 100 중량%를 기준으로 Ag를 10 내지 60 중량%, 15 내지 40 중량%, 또는 15 내지 30 중량%로 포함할 수 있으며, 음극 활물질층 전체 100 중량%를 기준으로 탄소재를 40 내지지 90 중량%, 60 내지 85 중량%, 또는 70 내지 85 중량%로 포함할 수 있다.The layer disposed adjacent to the solid electrolyte may include 10 to 60% by weight, 15 to 40% by weight, or 15 to 30% by weight of Ag based on 100% by weight of the total negative electrode active material layer, and the entire negative electrode active material layer Based on 100% by weight, the carbon material may be included at 40 to 90% by weight, 60 to 85% by weight, or 70 to 85% by weight.
또한, 상기 고체 전해질에 인접하여 배치되는 음극 활물질층은 바인더를 더 포함할 수 있으며, 이 경우, Ag 10 내지 55 중량%, 탄소재 40 내지 85 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있으며, 또한, Ag 15 내지 30 중량%, 탄소재 65 내지 83 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있다.In addition, the negative electrode active material layer disposed adjacent to the solid electrolyte may further include a binder. In this case, it may include 10 to 55% by weight of Ag, 40 to 85% by weight of carbon material, and 1 to 10% by weight of binder. It may also include 15 to 30% by weight of Ag, 65 to 83% by weight of carbon material, and 1 to 10% by weight of binder.
본 발명의 일 실시형태에 있어서, 상기 탄소재와 Ag를 포함하는 2개의 층은 각각 독립적으로 1㎛ 내지 50㎛의 두께를 가질 수 있다. In one embodiment of the present invention, the two layers including the carbon material and Ag may each independently have a thickness of 1 μm to 50 μm.
본 발명의 일 실시형태에 있어서, 도 2 또는 도 3에 예시된 바와 같이, 본 발명의 전고체 리튬이온 이차전지는 상기 탄소재와 Ag를 포함하는 2개의 층(24a, 24b) 이외에 음극 활물질 전체 100 중량%를 기준으로 Ag 0 내지 5 중량%, 또는 0 내지 2 중량%를 포함하는 층(24c)을 더 포함할 수 있다. 상기 층은 탄소재 95 내지 100 중량% 또는 98 내지 100 중량%를 더 포함할 수 있다. 또한, 상기 층이 바인더를 포함하는 경우에는 Ag 0 내지 5 중량%, 탄소재 90 내지 99 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있으며, 또한, Ag 0 내지 2 중량%, 탄소재 90 내지 99 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있다. In one embodiment of the present invention, as illustrated in Figure 2 or Figure 3, the all-solid lithium ion secondary battery of the present invention contains the entire negative electrode active material in addition to the two layers 24a and 24b containing the carbon material and Ag. It may further include a layer 24c containing 0 to 5% by weight, or 0 to 2% by weight, of Ag based on 100% by weight. The layer may further include 95 to 100% by weight or 98 to 100% by weight of carbon material. In addition, when the layer includes a binder, it may include 0 to 5% by weight of Ag, 90 to 99% by weight of carbon material, and 1 to 10% by weight of binder, and may also include 0 to 2% by weight of Ag and carbon material. It may include 90 to 99% by weight, and 1 to 10% by weight of binder.
본 발명의 일 실시형태에 있어서, 상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층은 Ag를 포함하지 않는 층으로 형성되는 것이 바람직할 수 있다. 또한, 상기 층은 바인더를 더 포함할 수 있으며, 이 경우, 탄소재 90 내지 99 중량%와 바인더 1 내지 10 중량%를 포함할 수 있다.In one embodiment of the present invention, it may be preferable that the layer containing 0 to 5% by weight of Ag and a carbon material is formed as a layer that does not contain Ag. In addition, the layer may further include a binder, and in this case, it may include 90 to 99% by weight of carbon material and 1 to 10% by weight of binder.
본 발명의 일 실시형태에 있어서, 도 3에 예시된 바와 같이, 상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층(24c)은 상기 탄소재와 Ag를 포함하는 2개의 층(24a, 24b) 사이에 배치되거나, 도 2에 예시된 바와 같이, 상기 2개의 층 중 고체 전해질 인접층(24b)과 고체 전해질(30) 사이에 배치될 수 있다.In one embodiment of the present invention, as illustrated in FIG. 3, the layer 24c containing 0 to 5% by weight of Ag and a carbon material is composed of two layers 24a and 24b containing the carbon material and Ag. ) or, as illustrated in FIG. 2, it may be disposed between the solid electrolyte adjacent layer 24b and the solid electrolyte 30 among the two layers.
본 발명의 일 실시형태에 있어서, 상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층(24c)은, 도 2에 예시된 바와 같이, 상기 2개의 층 중 고체 전해질 인접층(24b)과 고체 전해질(30) 사이에 배치되는 것이 바람직할 수 있다.In one embodiment of the present invention, the layer 24c containing 0 to 5% by weight of Ag and a carbon material is, as illustrated in FIG. 2, the solid electrolyte adjacent layer 24b and the solid electrolyte adjacent layer 24b of the two layers. It may be desirable to place it between the electrolytes 30.
본 발명의 일 실시형태에 있어서, 상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층(24c)은 1㎛ 내지 30㎛의 두께를 가질 수 있다. In one embodiment of the present invention, the layer 24c containing 0 to 5% by weight of Ag and a carbon material may have a thickness of 1 μm to 30 μm.
본 발명의 일 실시형태에 있어서, 본 발명의 음극 활물질층은 상기 탄소재와 Ag를 포함하는 2개의 층 이외에 음극 활물질층 전체 100 중량%를 기준으로 Ag를 80 내지 100 중량%, 90 내지 100 중량%, 또는 95 내지 100 중량%로 포함하는 층을 더 포함할 수 있다. 상기 층은 탄소재 0 내지 20 중량%, 0 내지 10 중량% 또는 0 내지 5 중량%를 더 포함할 수 있다. 또한, 상기 층은 바인더를 더 포함할 수 있으며, 이 경우, Ag 80 내지 99 중량%, 탄소재 0 내지 19 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있으며, Ag 90 내지 99 중량%, 탄소재 0 내지 9 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있으며, 또한, Ag 95 내지 99 중량%, 탄소재 0 내지 4 중량%, 및 바인더 1 내지 10 중량%를 포함할 수 있다.In one embodiment of the present invention, in addition to the two layers containing the carbon material and Ag, the negative electrode active material layer of the present invention contains 80 to 100% by weight and 90 to 100% by weight of Ag based on 100% by weight of the total negative electrode active material layer. %, or may further include a layer comprising 95 to 100% by weight. The layer may further include 0 to 20% by weight, 0 to 10% by weight, or 0 to 5% by weight of carbon material. In addition, the layer may further include a binder, in this case, 80 to 99% by weight of Ag, 0 to 19% by weight of carbon material, and 1 to 10% by weight of binder, and 90 to 99% by weight of Ag. , 0 to 9% by weight of carbon material, and 1 to 10% by weight of binder, and may also include 95 to 99% by weight of Ag, 0 to 4% by weight of carbon material, and 1 to 10% by weight of binder. there is.
본 발명의 일 실시형태에 있어서, 상기 Ag 80 내지 100 중량%로 포함하는 층은 상기 2개의 층 중 음극 집전체와 인접한 층과 음극 집전체 사이에 배치될 수 있다.In one embodiment of the present invention, the layer containing 80 to 100% by weight of Ag may be disposed between the negative electrode current collector and a layer adjacent to the negative electrode current collector among the two layers.
본 발명의 일 실시형태에 있어서, 상기 Ag 80 내지 100 중량%로 포함하는 층은 1㎛ 내지 30㎛의 두께를 가질 수 있다. In one embodiment of the present invention, the layer containing 80 to 100% by weight of Ag may have a thickness of 1㎛ to 30㎛.
본 발명의 일 실시형태에 있어서, 상기 2개 이상의 층은 탄소재와 Ag를 포함하는 1개의 층 및 Ag 0 내지 5 중량%와 탄소재를 포함하는 1개의 층을 포함하는 것일 수 있다. In one embodiment of the present invention, the two or more layers may include one layer containing carbon material and Ag and one layer containing 0 to 5% by weight of Ag and carbon material.
이 때, 상기 탄소재와 Ag를 포함하는 1개의 층은 상대적으로 집전체 쪽에 위치할 수 있으며, Ag 0 내지 5 중량%와 탄소재를 포함하는 1개의 층은 상대적으로 고체 전해질 쪽에 위치될 수 있다. 여기서 상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 1개의 층은 위에서 설명된 것과 동일하다. At this time, one layer containing the carbon material and Ag may be relatively located on the current collector side, and one layer including 0 to 5% by weight of Ag and the carbon material may be relatively located on the solid electrolyte side. . Here, one layer containing 0 to 5% by weight of Ag and carbon material is the same as described above.
본 발명의 일 실시형태에서, 상기 음극 활물질층에서 어느 하나 이상의 층에 포함되는 탄소재 입자는 예를 들어 비정질 탄소재 입자일 수 있다. 그러나 탄소재 입자가 비정질 입자로 한정되는 것은 아니다. 상기 비정질 탄소재의 구체적인 예로는, 아세틸렌블랙, 퍼니스블랙 및 케첸블랙 등의 카본블랙, 그래핀, 또는 이들 조합을 들 수 있다.In one embodiment of the present invention, the carbon material particles included in one or more layers in the negative electrode active material layer may be, for example, amorphous carbon material particles. However, carbon material particles are not limited to amorphous particles. Specific examples of the amorphous carbon material include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or a combination thereof.
상기 비정질 탄소재 입자가 기공들을 포함하는 경우, 상기 기공의 크기는 1 nm 이하, 바람직하게는 0.5 nm 이하일 수 있다. 그러나, 상기 비정질 탄소재 입자는 기공을 포함하지 않는 것이 더욱 바람직할 수 있다. 왜냐하면, 상기 비정질 탄소재 입자에 기공이 포함되는 경우, 상기 기공 내부에 리튬이 석출되고, 이러한 리튬이 불활성화될 수 있으며, 이와 같이 불활성화되는 리튬의 양은 충방전이 반복됨에 따라 증가될 수 있기 때문이다.When the amorphous carbon material particles include pores, the size of the pores may be 1 nm or less, preferably 0.5 nm or less. However, it may be more preferable that the amorphous carbon material particles do not contain pores. This is because, when the amorphous carbon material particles contain pores, lithium is precipitated inside the pores, and this lithium may be inactivated, and the amount of lithium thus inactivated may increase as charging and discharging are repeated. Because.
상기 비정질 탄소재 입자의 기공 크기는 예를 들어 질소 흡착 실험을 통하여 측정하거나, 투과전자현미경을 통하여 측정할 수 있다. The pore size of the amorphous carbon material particles can be measured, for example, through a nitrogen adsorption experiment or through a transmission electron microscope.
상기 탄소재 입자는 3 내지 10 at%의 산소를 포함하는 탄소재 입자일 수 있다. 상기에서 산소가 상술한 범위로 포함되는 경우, 음극 활물질층의 표면조도가 현저하게 개선될 수 있으며, 이에 따라 전지의 구동 특성도 개선되므로 바람직하다. 특히, Ag를 포함하는 층의 경우, 3 내지 10 at%의 산소를 포함하는 탄소재 입자를 포함하는 것이 바람직하다. The carbon material particles may be carbon material particles containing 3 to 10 at% oxygen. When oxygen is included in the above-mentioned range, the surface roughness of the negative electrode active material layer can be significantly improved, which is desirable because the driving characteristics of the battery are also improved. In particular, in the case of a layer containing Ag, it is preferable to contain carbon material particles containing 3 to 10 at% oxygen.
본 발명의 일 실시형태에서 상기 산소는 탄소재 입자에 결합된 관능기에 포함된 형태로 존재할 수 있다. 또한, 상기 관능기는 카르복시기, 하이드록시기, 에테르기, 에스테르기, 알데히드기, 카보닐기 및 아마이드기로 이루어진 군으로부터 선택되는 하나 이상을 포함하는 것일 수 있다. In one embodiment of the present invention, the oxygen may exist in a form included in a functional group bonded to the carbon material particle. Additionally, the functional group may include one or more selected from the group consisting of a carboxyl group, a hydroxy group, an ether group, an ester group, an aldehyde group, a carbonyl group, and an amide group.
상기 산소가 3 내지 10 at%로 포함된 탄소재 입자는 예를 들어, 탄소재를 산화시키는 방법으로 제조될 수 있다. 구체적으로, 탄소재를 산으로 처리하고, 25℃내지 60℃의 온도에서 교반하면서 반응시켜서 산소 작용기를 탄소재 표면에 도입할 수 있다. 상기 산의 종류는 특별히 제한되지 않으며, 탄소재의 표면에 산소 작용기를 도입할 수 있는 것이라면 어떠한 것도 가능하다. 상기 산으로는 예를 들어, 황산, 질산 또는 이들의 혼합물 등을 들 수 있으며, 과망산칼륨과 같은 산화제를 사용할 수도 있다.The carbon material particles containing 3 to 10 at% oxygen can be produced, for example, by oxidizing the carbon material. Specifically, the carbon material can be treated with acid and reacted with stirring at a temperature of 25°C to 60°C to introduce oxygen functional groups to the surface of the carbon material. The type of acid is not particularly limited, and any acid that can introduce an oxygen functional group to the surface of the carbon material can be used. Examples of the acid include sulfuric acid, nitric acid, or mixtures thereof, and an oxidizing agent such as potassium permangate may also be used.
상기 탄소재에 포함된 산소의 함량은 광전자 분광기(XPS 또는 ESCA)를 사용하여 측정될 수 있다. 예를 들어, K-Alpha(Thermo Fisher Scientific) 장치를 사용하여 측정될 수 있다. The content of oxygen contained in the carbon material can be measured using photoelectron spectroscopy (XPS or ESCA). For example, it can be measured using a K-Alpha (Thermo Fisher Scientific) device.
본 발명의 일 실시형태에 있어서, 상기 산소는 탄소재 입자의 표면에 존재하는 것일 수 있다. 상기 표면은 탄소재 입자의 외부 표면만 의미하는 것은 아니며, 기공이 존재하는 경우, 기공의 표면을 포함한다. In one embodiment of the present invention, the oxygen may be present on the surface of the carbon material particles. The surface does not mean only the outer surface of the carbon material particle, but includes the surface of the pores if pores exist.
본 발명의 일 실시형태에서, 상기 각 음극 활물질층은 Ag 입자 이외에 금, 백금, 팔라듐, 규소, 알루미늄, 비스무트, 주석, 인듐 및 아연으로부터 선택되는 1 종 이상의 입자를 더 포함할 수 있다.In one embodiment of the present invention, each negative electrode active material layer may further include one or more particles selected from gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc in addition to Ag particles.
본 발명의 일 실시형태에 있어서, 상기 탄소재 입자는 입도(D50)가 10nm 내지 100nm 또는 20nm 내지 60nm인 것이 사용될 수 있으며, 상기 Ag 입자 및 다른 금속 입자는 입도(D50)가 20nm 내지 100nm, 20nm 내지 60nm, 또는 30nm 내지 60nm인 것이 사용될 수 있다.In one embodiment of the present invention, the carbon material particles may have a particle size (D50) of 10 nm to 100 nm or 20 nm to 60 nm, and the Ag particles and other metal particles may have a particle size (D50) of 20 nm to 100 nm or 20 nm. to 60 nm, or 30 nm to 60 nm may be used.
본 발명의 일 실시형태에 있어서, 상기 음극 활물질층에 포함되는 어느 하나 이상의 층은 산소를 2 내지 10 at%로 포함하는 것일 수 있다. 산소가 상술한 범위로 포함되는 경우, 해당 층의 표면조도가 현저하게 개선되며, 이에 따라 전지의 구동 특성이 개선될 수 있으므로 바람직하다. In one embodiment of the present invention, one or more layers included in the negative electrode active material layer may contain 2 to 10 at% of oxygen. When oxygen is included in the above-mentioned range, the surface roughness of the layer is significantly improved, which is desirable because the driving characteristics of the battery can be improved.
상기 음극 활물질층에 포함되는 층 중 탄소재와 Ag를 포함하는 어느 하나 이상의 층은 상기 산소와 함께 탄소 65 내지 85 at% 및 Ag 0.5 내지 5 at%를 더 포함할 수 있으며, 더 바람직하게는 탄소 74 내지 85 at% 및 Ag 0.5 내지 3 at%를 더 포함할 수 있다.Among the layers included in the negative electrode active material layer, one or more layers containing a carbon material and Ag may further include 65 to 85 at% of carbon and 0.5 to 5 at% of Ag along with the oxygen, and more preferably carbon. It may further include 74 to 85 at% and 0.5 to 3 at% Ag.
상기 어느 하나 이상의 층은 5 내지 25 at%의 불소(F)를 더 포함할 수 있으며, 더 바람직하게는 10 내지 20 at%의 불소(F)를 더 포함할 수 있다.The one or more layers may further include 5 to 25 at% of fluorine (F), and more preferably may further include 10 to 20 at% of fluorine (F).
상기 어느 하나 이상의 층은 0.01 내지 1 at%의 황(S)을 더 포함할 수 있으며, 더 바람직하게는 0.01 내지 0.5 at%의 황(S)을 더 포함할 수 있다.Any one of the above layers may further include 0.01 to 1 at% of sulfur (S), and more preferably may further include 0.01 to 0.5 at% of sulfur (S).
본 발명의 일 실시형태에서, 상기 어느 하나 이상의 층은 산소 2 내지 10 at%, 탄소 65 내지 85 at%, Ag 0.5 내지 5 at%, 및 불소(F) 5 내지 25 at%를 포함할 수 있다. In one embodiment of the present invention, the one or more layers may include 2 to 10 at% oxygen, 65 to 85 at% carbon, 0.5 to 5 at% Ag, and 5 to 25 at% fluorine (F). .
또한, 더 바람직하게는 산소 2.5 내지 5 at%, 탄소 74 내지 85 at%, Ag 0.5 내지 3 at%, 및 불소(F) 10 내지 20 at%를 포함할 수 있다.Also, more preferably, it may contain 2.5 to 5 at% oxygen, 74 to 85 at% carbon, 0.5 to 3 at% Ag, and 10 to 20 at% fluorine (F).
또한, 상기 성분들에 추가로 상기 황(s)이 더 포함될 수도 있다.Additionally, sulfur (s) may be further included in addition to the above components.
상기에서 원자 성분비는 광전자 분광기(XPS 또는 ESCA)를 사용하여 측정될 수 있다. 예를 들어, 상기 성분비는 Nexsa4(Thermo Fisher Scientific) 장치를 사용하여 측정될 수 있다.In the above, the atomic composition ratio can be measured using photoelectron spectroscopy (XPS or ESCA). For example, the component ratio can be measured using a Nexsa4 (Thermo Fisher Scientific) device.
본 발명의 일 실시형태에서, 상기 상기 음극 활물질층에 포함되는 어느 하나 이상의 층은 다음의 표면조도를 갖는 특징을 가질 수 있다:In one embodiment of the present invention, any one or more layers included in the negative electrode active material layer may have the following surface roughness characteristics:
0.01 ㎛ ≤ Sa ≤ 0.3 ㎛0.01 ㎛ ≤ Sa ≤ 0.3 ㎛
0.5 ㎛ ≤ Sz ≤ 5 ㎛0.5 ㎛ ≤ Sz ≤ 5 ㎛
500 mm-1 ≤ Spc ≤ 1500 mm-1
500 mm -1 ≤ Spc ≤ 1500 mm -1
0.005 ≤ Sdr ≤ 0.15.0.005 ≤ Sdr ≤ 0.15.
표면조도가 상기 범위를 충족하는 경우, 전반적인 전지의 특성이 향상되며, 특히 수명특성이 향상될 수 있다. 구체적으로, 음극 활물질층의 표면조도가 상기 범위를 초과할 경우, 전해질 측 방향으로는 전해질층과 접촉이 충분히 이루어지지 않으며, 음극 집전체 측 방향으로는 리튬의 균일한 석출에 도움이 되지 않으므로, 전지의 특성을 저하시킬 수 있다.When the surface roughness meets the above range, the overall battery characteristics can be improved, and in particular, the lifespan characteristics can be improved. Specifically, if the surface roughness of the negative electrode active material layer exceeds the above range, sufficient contact with the electrolyte layer is not made in the direction of the electrolyte, and it is not conducive to uniform precipitation of lithium in the direction of the negative electrode current collector. This may deteriorate the characteristics of the battery.
상기에서 음극 활물질층의 표면조도는 현미경 장치를 사용하여 측정될 수 있다. 예를 들어, 3D 레이저 공초점 현미경(KEYENCE사 제조)장치를 사용하여 측정될 수 있다. In the above, the surface roughness of the negative electrode active material layer can be measured using a microscope device. For example, it can be measured using a 3D laser confocal microscope (manufactured by KEYENCE).
상기에서 Sa(프로파일의 산술 평균 높이)는 최대 0.3 ㎛ 이하, 0.2 ㎛ 이하, 0.1 ㎛ 이하, 0.08 ㎛ 이하, 또는 0.075 ㎛ 이하일 수 있으며, 최소 0.01 ㎛ 이상, 0.02 ㎛ 이상, 0.03 ㎛ 이상, 0.04 ㎛ 이상, 0.05 ㎛ 이상, 0.06 ㎛ 이상, 또는 0.07 ㎛ 이상일 수 있다. 또한, 상기 Sa는 0.01 ㎛ ≤ Sa ≤ 0.1 ㎛ 범위인 것이 더 바람직할 수 있으나, 이들 범위로 한정되는 것은 아니며, 상기 최대 값 및 최소 값의 조합 범위로 설정될 수 있다. 상기 Sa는 표면의 평균 면에 대해 각 점간 높이 차의 절대값의 평균값을 나타낸다. In the above, Sa (arithmetic mean height of the profile) may be at most 0.3 ㎛, 0.2 ㎛, 0.1 ㎛, 0.08 ㎛, or 0.075 ㎛, and at least 0.01 ㎛, 0.02 ㎛, 0.03 ㎛, 0.04 ㎛. It may be 0.05 ㎛ or more, 0.06 ㎛ or more, or 0.07 ㎛ or more. In addition, the Sa may be more preferably in the range of 0.01 ㎛ ≤ Sa ≤ 0.1 ㎛, but is not limited to these ranges and may be set to a combination of the maximum and minimum values. The Sa represents the average value of the absolute value of the height difference between each point with respect to the average plane of the surface.
상기에서 Sz(프로파일의 최대 높이 거칠기)는 최대 5 ㎛ 이하, 4 ㎛ 이하, 3 ㎛ 이하, 2 ㎛ 이하, 또는 1.5 ㎛ 이하일 수 있으며, 최소 0.5 ㎛ 이상, 0.8 ㎛ 이상, 1 ㎛ 이상, 1.1 ㎛ 이상, 1.2 ㎛ 이상, 또는 1.3 ㎛ 이상일 수 있다. 또한, 상기 Sz은 0.5 ㎛ ≤ Sz ≤ 1.6 ㎛ 범위인 것이 더 바람직할 수 있으나, 이들 범위로 한정되는 것은 아니며, 상기 최대 값 및 최소 값의 조합 범위로 설정될 수 있다. 상기 Sz은 단일면 내에서 최대 높이 거칠기로서, 단일 면 내에서 최고점과 최저점 간의 거리를 나타낸다.In the above, Sz (maximum height roughness of the profile) may be at most 5 ㎛, 4 ㎛, 3 ㎛, 2 ㎛, or 1.5 ㎛, and at least 0.5 ㎛, 0.8 ㎛, 1 ㎛, 1.1 ㎛. It may be more than 1.2 μm, or more than 1.3 μm. In addition, the Sz may be more preferably in the range of 0.5 ㎛ ≤ Sz ≤ 1.6 ㎛, but is not limited to these ranges and may be set to a combination of the maximum and minimum values. The Sz is the maximum height roughness within a single plane and represents the distance between the highest and lowest points within a single plane.
상기에서 Spc(피크 수에 의한 거칠기)는 최대 1500 mm-1 이하, 1400 mm-1 이하, 1300 mm-1 이하, 1200 mm-1 이하, 1100 mm-1 이하, 또는 1000 mm-1 이하일 수 있으며, 최소 500 mm-1 이상, 600 mm-1 이상, 700 mm-1 이상, 800 mm-1 이상, 또는 900 mm-1 이상일 수 있다. 또한, 500 mm-1 ≤ Spc ≤ 1100 mm-1 범위가 더 바람직할 수 있으나, 이들 범위로 한정되는 것은 아니며, 상기 최대 값 및 최소 값의 조합 범위로 설정될 수 있다. 상기 Spc는 피크수에 의한 거칠기로서 피크의 가파른 정도를 나타내는 척도이다.In the above, Spc (roughness by peak number) may be up to 1500 mm -1 or less, 1400 mm -1 or less, 1300 mm -1 or less, 1200 mm -1 or less, 1100 mm -1 or less, or 1000 mm -1 or less, , may be at least 500 mm -1 or more, 600 mm -1 or more, 700 mm -1 or more, 800 mm -1 or more, or 900 mm -1 or more. In addition, the range of 500 mm -1 ≤ Spc ≤ 1100 mm -1 may be more preferable, but is not limited to these ranges and may be set to a combination range of the maximum and minimum values. The Spc is roughness based on the number of peaks and is a measure of the steepness of the peak.
상기에서 Sdr(계면적 증가 정도)은 최대 0.15 이하, 0.1 이하, 0.05 이하, 0.03 이하, 또는 0.02 이하일 수 있으며, 최소 0.005 이상, 0.01 이상, 또는 0.015 이상일 수 있다. 또한, 0.005 ≤ Sa ≤ 0.03 범위가 더 바람직할 수 있으나, 이 범위로 한정되는 것은 아니며, 상기 최대 값 및 최소 값의 조합 범위로 설정될 수 있다. 상기 Sdr은 계면의 증가 정도로서, 전개 면적(측정한 형상의 표면적)의 측정 영역을 수직으로 볼 때의 면적 대비 증가한 면적비를 의미한다. In the above, Sdr (interfacial area increase degree) may be at most 0.15 or less, 0.1 or less, 0.05 or less, 0.03 or less, or 0.02 or less, and may be at least 0.005 or more, 0.01 or more, or 0.015 or more. Additionally, the range of 0.005 ≤ Sa ≤ 0.03 may be more preferable, but is not limited to this range and may be set to a combination range of the maximum and minimum values. The Sdr is the degree of increase in the interface and means the ratio of the area increased compared to the area when the measurement area of the developed area (surface area of the measured shape) is viewed vertically.
상기에서 Sa, Sz, Spc, 및 Sdr의 의미를 기재하고 있지만, 이는 이 분야에서 통상적으로 사용되는 의미와 동일한 의미로 사용된다.Although the meanings of Sa, Sz, Spc, and Sdr are described above, they are used in the same sense as those commonly used in this field.
본 발명의 일 실시형태에서, 상기 음극 활물질층에서 어느 하나 이상의 층에 포함되는 상기 탄소재 입자 및 Ag 입자는 탄소재-금속 복합체 형태로 포함될 수 있다.In one embodiment of the present invention, the carbon material particles and Ag particles included in one or more layers of the negative electrode active material layer may be included in the form of a carbon material-metal composite.
본 발명에서 상기 음극 활물질층은 마이크로 두께의 매우 얇은 박막으로 형성되며, 탄소재 입자와 Ag 입자가 결합된 탄소재-Ag 복합체를 포함하는 형태로 제조될 수 있다. 그런데, 상기 종래의 탄소재-Ag 복합체는 탄소재 입자와 Ag 입자가 균일하게 분포되기 어렵다는 문제가 있었다. In the present invention, the negative electrode active material layer is formed as a very thin film with a micro thickness, and can be manufactured in a form containing a carbon material-Ag composite in which carbon material particles and Ag particles are combined. However, the conventional carbon material-Ag composite had a problem in that it was difficult for the carbon material particles and Ag particles to be uniformly distributed.
더 나아가서, 종래의 탄소재-Ag 복합체는 입도를 작게 형성하는 것이 매우 어렵다는 문제가 있었다. 즉, 탄소재-Ag 복합체의 입도가 마이크로 두께의 박막대비 너무 클 경우 우수한 표면조도를 갖는 음극 활물질층을 형성하는 것이 어려우며, 이에 따라 전지의 구동 특성도 저하되므로, 탄소재-Ag 복합체의 입도를 작게 제조하는 것은 매우 중요하다. Furthermore, the conventional carbon material-Ag composite had a problem in that it was very difficult to form a small particle size. In other words, if the particle size of the carbon material-Ag composite is too large compared to the micro-thick thin film, it is difficult to form a negative electrode active material layer with excellent surface roughness, and the driving characteristics of the battery deteriorate accordingly. Therefore, the particle size of the carbon material-Ag composite is reduced. Manufacturing small is very important.
본 발명은 종래 기술의 상기와 같은 문제를 획기적으로 개선하는 효과를 제공한다.The present invention provides the effect of dramatically improving the above problems of the prior art.
즉, 상기 탄소재-Ag 복합체는 종래의 탄소재를 사용하는 경우와 비교하여 입도가 현저히 작은 탄소재-Ag 복합체를 형성한다. 상기 복합체를 형성하는 상기 탄소재는 상기 산소가 3 at% 이상 포함되어 금속 입자와 잘 혼합되고, Ag 입자와 균일하게 분포되는 특성을 갖는다. 따라서 성분 균일도가 우수한 탄소재-Ag 복합체를 제조하는 것을 가능하게 한다. 또한, 위와 같은 이유로 작고 균일한 입도의 탄소재-Ag 복합체를 제조하는 것을 가능하게 한다.That is, the carbon material-Ag composite forms a carbon material-Ag composite with a significantly smaller particle size compared to the case of using a conventional carbon material. The carbon material forming the composite contains more than 3 at% of oxygen, mixes well with the metal particles, and has the property of being uniformly distributed with the Ag particles. Therefore, it is possible to manufacture a carbon material-Ag composite with excellent component uniformity. Additionally, for the above reasons, it is possible to manufacture a carbon material-Ag composite with small and uniform particle size.
본 발명의 일 실시형태에 있어서, 상기 탄소재-Ag 복합체는 탄소재 입자와 Ag 입자의 화학 결합, 탄소재 입자와 Ag 입자의 반데르발스 결합, 및 탄소재 입자와 Ag 입자의 바인더에 의한 결합 중에서 선택되는 하나 이상의 결합에 의해 구성된 것일 수 있다. 상기 화학결합은 Ag 입자와 탄소재에 포함된 산소와의 Ag-O 결합일 수 있다.In one embodiment of the present invention, the carbon material-Ag composite is a chemical bond between carbon material particles and Ag particles, a van der Waals bond between carbon material particles and Ag particles, and a bond between carbon material particles and Ag particles by a binder. It may be composed of one or more combinations selected from among. The chemical bond may be an Ag-O bond between Ag particles and oxygen contained in the carbon material.
본 발명의 일 실시형태에 있어서, 상기 탄소재 입자는 입도(D50)가 10nm 내지 100nm 또는 20nm 내지 60nm인 것이 사용될 수 있으며, 상기 Ag 입자는 입도(D50)가 20nm 내지 100nm, 20nm 내지 60nm, 또는 30nm 내지 60nm인 것이 사용될 수 있다.In one embodiment of the present invention, the carbon material particles may have a particle size (D50) of 10 nm to 100 nm or 20 nm to 60 nm, and the Ag particles may have a particle size (D50) of 20 nm to 100 nm, 20 nm to 60 nm, or 30nm to 60nm can be used.
본 발명의 일 실시형태에 있어서, 상기 탄소재-Ag 복합체의 입도(D50)는 0.1㎛ 내지 0.5㎛일 수 있다. 상기 입도의 상한 값은 0.4㎛ 또는 0.3㎛일 수 있다. In one embodiment of the present invention, the particle size (D50) of the carbon material-Ag composite may be 0.1㎛ to 0.5㎛. The upper limit of the particle size may be 0.4㎛ or 0.3㎛.
또한, 상기 탄소재-Ag 복합체의 최대 입자 사이즈는 3㎛ 이하, 2㎛ 이하, 1.5㎛ 이하, 1㎛ 이하일 수 있다.Additionally, the maximum particle size of the carbon material-Ag composite may be 3 μm or less, 2 μm or less, 1.5 μm or less, and 1 μm or less.
상기 탄소재-Ag 복합체의 입도가 마이크로 두께의 박막대비 너무 클 경우 우수한 표면조도를 갖는 음극 활물질층을 형성하는 것이 어려우며, 이에 따라 전지의 구동 특성도 저하되므로, 탄소재-Ag 복합체의 입도를 작게 제조하는 것은 매우 중요하다. If the particle size of the carbon material-Ag composite is too large compared to the micro-thick thin film, it is difficult to form a negative active material layer with excellent surface roughness, and the driving characteristics of the battery deteriorate accordingly, so the particle size of the carbon material-Ag composite is reduced. Manufacturing is very important.
상기 전지의 구동 특성이 저하되는 이유는 음극 활물질층의 표면조도가 클 경우, 전해질층과 접촉이 충분히 이루어지지 않으며, 음극 집전체에 대한 리튬의 균일한 석출에 도움이 되지 않기 때문이다. The reason why the driving characteristics of the battery deteriorate is because when the surface roughness of the negative electrode active material layer is large, sufficient contact is not made with the electrolyte layer and it is not conducive to uniform precipitation of lithium on the negative electrode current collector.
애노드 리스 리튬이온 이차전지에서 음극 활물질층의 두께는 통상적으로 1 ㎛ 내지 100 ㎛, 또는 10 ㎛ 내지 60 ㎛ 범위로 형성될 수 있으며, 구체적으로는 10㎛, 20㎛, 30㎛, 40㎛, 50㎛ 등의 두께로 형성될 수 있다. In an anode-less lithium ion secondary battery, the thickness of the negative electrode active material layer can typically range from 1 ㎛ to 100 ㎛, or 10 ㎛ to 60 ㎛, specifically 10 ㎛, 20 ㎛, 30 ㎛, 40 ㎛, and 50 ㎛. It may be formed to a thickness of ㎛ or the like.
예를 들어, 두께가 20㎛인 음극 활물질층을 형성하는데, 입도가 10㎛인 탄소재-Ag 복합체를 사용한다면, 바람직한 표면조도를 형성하기 어려운 것은 자명하다.For example, if a carbon material-Ag composite with a particle size of 10 μm is used to form a negative electrode active material layer with a thickness of 20 μm, it is obvious that it is difficult to form a desirable surface roughness.
상기 탄소재-금속 복합체의 최대 입도가 3㎛ 이하일 경우, 표면조도 향상 효과를 더 확실하게 얻을 수 있으므로 바람직하다. 반면, 3㎛를 초과할 경우에는 박막의 형성시 우수한 표면조도를 얻기 어려울 수 있다. 그러므로, 상기 탄소재-Ag 복합체의 최대 입자 사이즈는 3㎛ 이하, 2㎛ 이하, 1.5㎛ 이하, 1㎛ 이하일 수 있다. When the maximum particle size of the carbon material-metal composite is 3㎛ or less, it is preferable because the effect of improving surface roughness can be more reliably obtained. On the other hand, if it exceeds 3㎛, it may be difficult to obtain excellent surface roughness when forming a thin film. Therefore, the maximum particle size of the carbon material-Ag composite may be 3 μm or less, 2 μm or less, 1.5 μm or less, and 1 μm or less.
상기 탄소재-Ag 복합체의 입도는 입도분석기를 사용하여 측정될 수 있다. 예를 들어, Mastersizer 3000(Malvem panalytical) 기기를 사용하여 측정될 수 있다.The particle size of the carbon material-Ag composite can be measured using a particle size analyzer. For example, it can be measured using a Mastersizer 3000 (Malvem panalytical) instrument.
본 발명의 일 실시형태에 있어서, 상기 양극은 양극 집전체와 양극 활물질층을 포함할 수 있다. In one embodiment of the present invention, the positive electrode may include a positive electrode current collector and a positive electrode active material layer.
본 발명의 일 실시형태에 있어서, 상기 고체 전해질은 황화물계 고체 전해질일 수 있다. In one embodiment of the present invention, the solid electrolyte may be a sulfide-based solid electrolyte.
이하에서 본 발명의 실시형태에 대하여 더 구체적으로 설명한다.Hereinafter, embodiments of the present invention will be described in more detail.
<전고체 리튬이온 이차전지의 구성><Configuration of all-solid-state lithium-ion secondary battery>
도 1은 본 발명의 일 구현예에 따른 전고체 리튬이온 이차전지의 개략적인 구성을 개략적으로 나타낸 단면도이다.Figure 1 is a cross-sectional view schematically showing the schematic configuration of an all-solid lithium ion secondary battery according to an embodiment of the present invention.
본 발명의 일 실시형태에 따른 전고체 리튬이온 이차전지(100)는 양극(10)과 음극(20) 사이를 리튬이온이 이동함으로써 충방전을 실시하는, 소위 리튬이온 이차전지이다. 구체적으로 이 전고체 리튬이온 이차전지(100)는, 도 1에서 보이는 바와 같이, 양극(10), 음극(20), 및 양극(10)과 음극(20) 사이에 배치된 고체 전해질층(30)으로 구성된다.The all-solid lithium ion secondary battery 100 according to an embodiment of the present invention is a so-called lithium ion secondary battery that performs charging and discharging by moving lithium ions between the positive electrode 10 and the negative electrode 20. Specifically, as shown in FIG. 1, this all-solid lithium ion secondary battery 100 includes a positive electrode 10, a negative electrode 20, and a solid electrolyte layer 30 disposed between the positive electrode 10 and the negative electrode 20. ) is composed of.
(1) 양극(1) anode
도 1에 도시된 바와 같이, 양극(10)은 음극(20)을 향하여 차례로 배치된 양극 집전체(12) 및 양극 활물질층(14)을 포함한다.As shown in FIG. 1, the positive electrode 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14 sequentially disposed toward the negative electrode 20.
양극 집전체(12)는 판상 또는 포일상(foil)일 수 있다. 양극 집전체(12)는, 예를 들어, 인듐, 구리, 마그네슘, 스테인레스 스틸, 티타늄, 철, 코발트, 니켈, 아연, 알루미늄, 게르마늄, 리튬으로부터 선택되는 1 종의 금속 또는 2종 이상의 금속의 합금일 수 있다.The positive electrode current collector 12 may be plate-shaped or foil-shaped. The positive electrode current collector 12 is, for example, one metal selected from indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, and lithium, or an alloy of two or more metals. It can be.
양극 활물질층(14)은 리튬이온을 가역적으로 흡장 및 방출할 수 있다. 양극 활물질층(14)은 양극 활물질 및 고체 전해질을 포함할 수 있다.The positive active material layer 14 can reversibly store and release lithium ions. The positive electrode active material layer 14 may include a positive electrode active material and a solid electrolyte.
상기 양극 활물질은 리튬의 삽입/탈리가 가능한 화합물일 수 있다. 상기 리튬의 삽입/탈리가 가능한 화합물의 예로는, LiaA1-bB'bD'2(상기 식에서, 0.90≤a≤1.8, 및 0≤b≤0.5이다); LiaE1-bB'bO2-cD'c(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05이다); LiE2-bB'bO4-cD'c(상기 식에서, 0≤b≤0.5, 0≤c≤0.05이다); LiaNi1-b-cCobB'cD'α(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2이다); LiaNi1-b-cCobB'cO2-αF'α(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α＜2이다); LiaNi1-b-cMnbB'cD'α(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2이다); LiaNi1-b-cMnbB'cO2-αF'α(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2이다); LiaNibEcGdO2(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤ 0.1이다.); LiaNibCocMndGeO2(상기 식에서, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1이다.); LiaNiGbO2(상기 식에서, 0.90≤a≤1.8, 0.001≤b≤0.1이다.); LiaCoGbO2(상기식에서, 0.90≤a≤1.8, 0.001≤b≤0.1이다.); LiaMnGbO2(상기 식에서, 0.90≤a≤1.8, 0.001≤b≤0.1이다.); LiaMn2GbO4(상기 식에서, 0.90≤a≤1.8, 0.001≤b≤0.1이다.); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI'O2; LiNiVO4; Li(3-f)J2(PO4)3(0≤f≤2); Li(3-f)Fe2(PO4)3(0≤f≤2); LiFePO4의 화학식 중 어느 하나로 표현되는 것을 들 수 있다.The positive electrode active material may be a compound capable of insertion/desorption of lithium. Examples of compounds capable of insertion/detachment of lithium include Li a A 1-b B' b D' 2 (in the above formula, 0.90≤a≤1.8 and 0≤b≤0.5); Li a E 1 - b B' b O 2-c D' c (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B' b O 4-c D' c (in the above formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-bc Co b B' c D' α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-bc Co b B' c O 2-α F' α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-bc Mn b B' c D' α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-bc Mn b B' c O 2-α F' α (in the above formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O 2 (In the above formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤ 0.1); Li a Ni b Co c Mn d G e O 2 (In the above formula, 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O 2 (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O 2 (In the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a MnG b O 2 (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 2 G b O 4 (in the above formula, 0.90≤a≤1.8, 0.001≤b≤0.1); QO 2 ; QS 2 ; LiQS 2 ; V 2 O 5 ; LiV 2 O 5 ; LiI'O 2 ; LiNiVO 4 ; Li (3-f) J 2 (PO 4 ) 3 (0≤f≤2); Li (3-f) Fe 2 (PO 4 ) 3 (0≤f≤2); It may be expressed in any one of the chemical formulas of LiFePO 4 .
상기 화학식에 있어서, A는 Ni, Co, Mn, 또는 이들의 조합이고; B'는 Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, 희토류 원소 또는 이들의 조합이고; D'는 O, F, S, P, 또는 이들의 조합이고; E는 Co, Mn, 또는 이들의 조합이고; F'는 F, S, P, 또는 이들의 조합이고; G는 Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, 또는 이들의 조합이고; Q는 Ti, Mo, Mn, 또는 이들의 조합이고; I'는 Cr, V, Fe, Sc, Y, 또는 이들의 조합이며; J는 V, Cr, Mn, Co, Ni, Cu, 또는 이들의 조합이다.In the above formula, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D' is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.
상기 양극 활물질의 구체적인 예로는, 코발트산 리튬(이하 LCO라 함), 니켈 산 리튬, 니켈코발트산 리튬, 니켈코발트알루미늄산 리튬(이하, NCA이라 함), 니켈코발트망간산 리튬(이하 NCM이라 함), 망간산 리튬 및 리튬철인산염 등의 리튬염, 및 황화리튬 등을 들 수 있다. 양극 활물질층(14)은 양극 활물질로서 이러한 화합물에서 선택되는 1 종만을 포함할 수 있고, 또한 2종 이상을 포함할 수 있다.Specific examples of the positive electrode active material include lithium cobaltate (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobaltate, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), and lithium nickel cobalt manganate (hereinafter referred to as NCM). ), lithium salts such as lithium manganate and lithium iron phosphate, and lithium sulfide. The positive electrode active material layer 14 may contain only one type selected from these compounds as the positive electrode active material, or may contain two or more types.
상기 양극 활물질은 상술한 리튬염 중 층상 암염형 구조를 갖는 전이금속 산화물의 리튬염을 포함할 수 있다. 여기에서, 「층상 암염형 구조」는 입방정 암염형 구조의 방향으로 산소 원자층과 금속 원자층이 교대로 규칙적으로 배열하고 그 결과 각각의 원자층이 이차원 평면을 형성하고 있는 구조이다. 또한 「입방정 암염형 구조」는 결정 구조의 1종인 염화나트륨형 구조인 것을 의미한다. 예를 들어, 「입방정 암염형 구조」는 양이온 및 음이온 각각 형성된 면심 입방 격자가 서로 단위격자의 모서리의 1/2만큼 어긋나서 배치된 구조를 나타낸다.The positive electrode active material may include a lithium salt of a transition metal oxide having a layered halite-type structure among the lithium salts described above. Here, the “layered rock salt structure” is a structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in the direction of the cubic rock salt structure, and as a result, each atomic layer forms a two-dimensional plane. Additionally, “cubic rock salt type structure” means a sodium chloride type structure, which is a type of crystal structure. For example, the “cubic rock salt structure” refers to a structure in which face-centered cubic lattices formed of cations and anions are offset from each other by 1/2 of the edges of the unit lattice.
이러한 층상 암염형 구조를 갖는 전이금속 산화물의 리튬염으로는, 예를 들어, LiNixCoyAlzO2(NCA) 또는 LiNixCoyMnzO2(NCM) (단, 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1) 등과 같은 삼원계 리튬 전이금속 산화물일 수 있다. 양극 활물질층(14)은 이러한 층상 암염형 구조를 갖는 삼원계 전이금속 산화물의 리튬염을 양극 활물질로 포함하여 전고체 리튬이온 이차전지(100)의 에너지 밀도 및 열 안정성을 향상시킬 수 있다.Examples of the lithium salt of a transition metal oxide having such a layered rock salt structure include LiNi x Co y Al z O 2 (NCA) or LiNi x Co y Mn z O 2 (NCM) (where 0 < x < It may be a ternary lithium transition metal oxide such as 1, 0 < y < 1, 0 < z < 1, x + y + z = 1). The positive electrode active material layer 14 may include a lithium salt of a ternary transition metal oxide having such a layered rock salt-type structure as a positive electrode active material, thereby improving the energy density and thermal stability of the all-solid-state lithium ion secondary battery 100.
여기서, 양극 활물질의 형상으로는, 예를 들어, 진구형, 타원 구형 등의 입자 형상을 들 수 있다. 또한 양극 활물질의 입경은 특별히 제한되지 않으며, 통상적인 전고체 리튬이온 이차전지의 양극 활물질에 적용가능한 범위이면 된다. 또한, 양극 활물질층(14)에서 양극 활물질의 함량도 특별히 제한되지 않고, 통상적인 전고체 리튬이온 이차전지의 양극에 적용 가능한 범위 내라면 가능하다.Here, examples of the shape of the positive electrode active material include particle shapes such as spherical shape and elliptical sphere shape. Additionally, the particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to the positive electrode active material of a typical all-solid lithium ion secondary battery. In addition, the content of the positive electrode active material in the positive electrode active material layer 14 is not particularly limited, and can be applied as long as it is within the range applicable to the positive electrode of a typical all-solid lithium ion secondary battery.
물론, 상기 화합물 표면에 코팅층을 갖는 것도 사용할 수 있고, 또는 상기 화합물과 코팅층을 갖는 화합물을 혼합하여 사용할 수도 있다. 이 코팅층은 코팅 원소의 옥사이드, 하이드록사이드, 코팅 원소의 옥시하이드록사이드, 코팅 원소의 옥시카보네이트, 또는 코팅 원소의 하이드록시카보네이트의 코팅 원소 화합물을 포함할 수 있다. 이들 코팅층을 이루는 화합물은 비정질 또는 결정질일 수 있다. 상기 코팅층에 포함되는 코팅 원소로는 Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr 또는 이들의 혼합물을 들 수 있다. 코팅층 형성 공정은 상기 화합물에 이러한 원소들을 사용하여 양극 활물질의 물성에 악영향을 주지 않는 방법(예를 들어 스프레이 코팅, 침지법 등)으로 코팅할 수 있으면 어떠한 코팅방법을 사용하여도 무방하며, 이에 대하여는 이 분야에 종사하는 사람들에게 잘 이해될 수 있는 내용이므로 자세한 설명은 생략하기로 한다. Of course, a compound having a coating layer on the surface of the above compound may be used, or a mixture of the above compound and a compound having a coating layer may be used. This coating layer may include a coating element compound of an oxide, hydroxide, oxyhydroxide of the coating element, oxycarbonate of the coating element, or hydroxycarbonate of the coating element. The compounds that make up these coating layers may be amorphous or crystalline. Coating elements included in the coating layer include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. For the coating layer formation process, any coating method may be used as long as the above compounds can be coated with these elements in a manner that does not adversely affect the physical properties of the positive electrode active material (e.g., spray coating, dipping method, etc.). Since this is well-understood by people working in this field, detailed explanation will be omitted.
상기 코팅층의 구체적인 예로는 Li2O-ZrO2 등을 들 수 있다.Specific examples of the coating layer include Li 2 O-ZrO 2 and the like.
양극 활물질층(14)에 포함되는 고체 전해질은 후술하는 고체 전해질층(30)에 포함되는 고체 전해질과 동종일 수도 있고 다른 것일 수도 있다.The solid electrolyte included in the positive electrode active material layer 14 may be the same as or different from the solid electrolyte included in the solid electrolyte layer 30, which will be described later.
또한, 양극 활물질층(14)은 상술한 양극 활물질 및 고체 전해질뿐만 아니라, 예를 들어, 도전제, 결착제(바인더), 필러(filler), 분산제, 또는 이온 전도성 보조제 등의 첨가제를 적절히 배합한 것일 수도 있다.In addition, the positive electrode active material layer 14 is formed by appropriately mixing not only the positive electrode active material and solid electrolyte described above, but also additives such as, for example, a conductive agent, binder, filler, dispersant, or ion conductive auxiliary agent. It may be.
상기 도전제로는, 예를 들어, 흑연, 카본블랙, 아세틸렌 블랙, 케첸(Ketjen) 블랙, 카본섬유, 또는 금속분말 등을 들 수 있다. 또한 상기 결착제(바인더)로는, 예를 들어, 스티렌부타디엔 고무(SBR), 폴리테트라플루오로에틸렌(polytetrafluoroethylene), 폴리불화비닐리덴(polyvinylidene fluoride), 또는 폴리에틸렌(polyethylene) 등을 들 수 있다. 또한 상기 필러(filler), 분산제, 또는 이온 전도성 보조제 등으로는 통상적으로 전고체 리튬이온 이차전지의 전극에 사용되는 공지의 재료를 사용할 수 있다.Examples of the conductive agent include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or metal powder. Also, examples of the binder (binder) include styrenebutadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, or polyethylene. In addition, known materials commonly used in electrodes of all-solid-state lithium ion secondary batteries can be used as the filler, dispersant, or ion conductive auxiliary agent.
(2) 음극(2) cathode
음극(20)은 양극(10)을 향해 차례로 배치된 음극 집전체(22) 및 음극 활물질층(24)을 포함할 수 있다.The negative electrode 20 may include a negative electrode current collector 22 and a negative electrode active material layer 24 sequentially disposed toward the positive electrode 10 .
음극 집전체(22)는 판상 또는 포일상(foil)일 수 있다. 음극 집전체(22)는, 리튬과 반응하지 않는, 즉 리튬과 합금 및 화합물 중 어느 것도 형성하지 않는 재료를 포함할 수 있다. 음극 집전체(22)를 구성하는 재료로는, 예를 들면, 구리, 스테인레스 스틸, 티타늄, 철, 코발트 및 니켈 등을 들 수 있다. 음극 집전체(22)는, 이들 금속 중에서 1종으로 구성되어 있을 수도 있고, 2종 이상의 금속의 합금 또는 클래드(clad, 피복) 재료로 구성되어 있을 수도 있다.The negative electrode current collector 22 may be plate-shaped or foil-shaped. The negative electrode current collector 22 may include a material that does not react with lithium, that is, does not form any alloy or compound with lithium. Materials constituting the negative electrode current collector 22 include, for example, copper, stainless steel, titanium, iron, cobalt, and nickel. The negative electrode current collector 22 may be composed of one type of these metals, or may be composed of an alloy or clad material of two or more types of metals.
음극 활물질층(24)은 리튬과 합금 또는 화합물의 형성이 가능한 음극 활물질을 1 종 또는 2 종 이상 포함할 수 있다. 초기 상태 또는 완전 방전후 상태에서 상기 음극 집전체(22), 상기 음극 활물질층(24), 또는 상기 음극 활물질층(24)과 고체 전해질층(30) 사이에는 리튬이 포함되지 않을 수 있다. 후술하는 바와 같이, 일 구현예에 따른 전고체 리튬이온 이차전지(100)를 과충전하면, 음극 활물질층(24)이 함유하는 음극 활물질과 양극(10)에서 이동해온 리튬이온이 합금 또는 화합물을 형성하고 도 4와 같이 리튬을 주성분으로하는 금속층(26)이 음극(20)에 형성(석출)될 수 있다. 상기 금속층(26)은 상기 음극 집전체(22)와 상기 음극 활물질층(24) 사이, 상기 음극 활물질층(24)의 내부, 또는 이들 모두에 석출되어 배치될 수 있다. 상기 음극 집전체(22)와 상기 음극 활물질층(24) 사이에서 상기 리튬을 주성분으로 하는 금속층(26)은 상기 음극 활물질층(24) 보다 음극 집전체층(22)에 근접하여 배치될 수 있다.The negative electrode active material layer 24 may include one or two or more types of negative electrode active materials capable of forming an alloy or compound with lithium. In the initial state or the state after complete discharge, lithium may not be contained in the negative electrode current collector 22, the negative electrode active material layer 24, or between the negative electrode active material layer 24 and the solid electrolyte layer 30. As will be described later, when the all-solid lithium ion secondary battery 100 according to one embodiment is overcharged, the negative electrode active material contained in the negative electrode active material layer 24 and the lithium ions moving from the positive electrode 10 form an alloy or compound. And as shown in FIG. 4, a metal layer 26 containing lithium as a main component may be formed (precipitated) on the cathode 20. The metal layer 26 may be deposited and disposed between the negative electrode current collector 22 and the negative electrode active material layer 24, inside the negative electrode active material layer 24, or both. Between the negative electrode current collector 22 and the negative electrode active material layer 24, the metal layer 26 mainly containing lithium may be disposed closer to the negative electrode current collector layer 22 than the negative electrode active material layer 24. .
일 구현예에 따른 음극 활물질층(24)은 필수 음극 활물질로서 Ag를 포함할 수 있다. 따라서 과충전시 형성되는 금속층(26)은 리튬 중에 Ag가 고용된 γ1 상, βLi 상 또는 이들 조합의 상을 포함한 Li(Ag) 합금을 포함할 수 있다. 따라서 방전시에는 금속층(26)을 구성하는 Li(Ag) 합금에서 Li만 용해하고 고용한 Ag가 잔존하여 공극의 발생을 억제할 수 있다. 이 경우, 석출한 Li-Ag 고용체에서 Ag의 함량은 60 중량% 이하일 수 있다. 이와 같은 범위라면, Ag의 영향에 의한 평균 방전전위의 저하를 효과적으로 억제할 수 있다. 한편, 석출한 Li-Ag 고용체 중의 Ag의 함량이 너무 적으면, 방전시에 잔존하는 Ag의 양이 적어지고, 공극의 발생을 충분히 억제할 수 없을 수 있다. 이 때문에, 석출한 Li-Ag 고용체 중의 Ag의 함량은 20 중량% 이상, 예를 들어 40 중량% 이상일 수 있다.The anode active material layer 24 according to one embodiment may include Ag as an essential anode active material. Therefore, the metal layer 26 formed during overcharging may include a Li(Ag) alloy including a γ1 phase in which Ag is dissolved in lithium, a βLi phase, or a combination thereof. Therefore, during discharge, only Li is dissolved in the Li(Ag) alloy constituting the metal layer 26, and the dissolved Ag remains, thereby suppressing the generation of voids. In this case, the content of Ag in the precipitated Li-Ag solid solution may be 60% by weight or less. Within this range, the decrease in average discharge potential due to the influence of Ag can be effectively suppressed. On the other hand, if the content of Ag in the precipitated Li-Ag solid solution is too small, the amount of Ag remaining during discharge decreases, and the generation of voids may not be sufficiently suppressed. For this reason, the content of Ag in the precipitated Li-Ag solid solution may be 20% by weight or more, for example, 40% by weight or more.
금속층(26)이 γ1 상 또는 βLi 상의 적어도 하나의 Li-Ag 고용체를 포함하는 것은, 예를 들면 XRD 측정에 의한 피크위치와 피크 강도비를 분석하여 확인할 수 있다. 또한 석출한 Li-Ag 고용체 중의 Ag 함량은, 예를 들어 XRD 측정에 의해 측정될 수 있다. 이 경우 순수한 금속 리튬과 Ag가 고용한 금속 리튬(Li-Ag 고용체)과는 회절 피크위치가 다르다. Ag가 고용한 금속 리튬의 회절 피크위치는 Ag의 고용농도가 내려갈수록 순수한 금속리튬의 피크 위치에 접근한다. 예를 들어, Cu 타겟을 이용한 XRD 측정에서는, Ag의 고용농도가 낮아지면 회절 피크가 2θ = 37.0° 부근에서 36.5° 부근으로 이동한다. 이 피크위치에서 Ag의 고용량을 추정할 수 있다. 이외에도, ICP 등으로도 고용량을 측정할 수 있다.That the metal layer 26 contains at least one Li-Ag solid solution of the γ 1 phase or the βLi phase can be confirmed by, for example, analyzing the peak position and peak intensity ratio by XRD measurement. Additionally, the Ag content in the precipitated Li-Ag solid solution can be measured, for example, by XRD measurement. In this case, the diffraction peak positions are different from pure metallic lithium and metallic lithium dissolved in Ag (Li-Ag solid solution). The diffraction peak position of metallic lithium dissolved in Ag approaches that of pure metallic lithium as the dissolved solid concentration of Ag decreases. For example, in XRD measurement using a Cu target, when the solid solution concentration of Ag decreases, the diffraction peak moves from around 2θ = 37.0° to around 36.5°. The solid capacity of Ag can be estimated from this peak position. In addition, high capacity can be measured using ICP, etc.
일 구현예에서는, Ag는 음극 활물질층(24)에 반드시 균일하게 존재하고 있을 필요는 없고, 음극 활물질층(24) 중에서 음극 집전체(22) 측에 편재되어 있을 수 있다. 이 경우, 리튬이온이 음극 집전체(22) 근방에 도달한 음극 활물질층(24) 중의 Ag 편재층과 반응함으로써 Li(Ag) 합금이 금속층(26)으로 형성될 수 있다.In one embodiment, Ag does not necessarily have to exist uniformly in the negative electrode active material layer 24, but may be localized on the negative electrode current collector 22 side of the negative electrode active material layer 24. In this case, lithium ions react with the Ag localization layer in the negative electrode active material layer 24 that has reached the vicinity of the negative electrode current collector 22, thereby forming a Li(Ag) alloy into the metal layer 26.
음극 활물질층(24)이 포함하는 Ag의 함량이 너무 작으면, 방전시에 잔존하는 Ag도 줄어들기 때문에 공극의 발생을 억제할 수 없게 될 수 있다. 이 때문에, 음극 활물질층(24)은 충방전을 하지 않은 초기상태에서, 음극 활물질층에 포함된 음극 활물질 전체 100 중량%를 기준으로, Ag를 10 중량% 이상, 예를 들어 20 중량% 이상 포함할 수 있다.If the content of Ag contained in the negative electrode active material layer 24 is too small, the Ag remaining during discharge may also decrease, making it impossible to suppress the generation of voids. For this reason, the negative electrode active material layer 24 contains 10% by weight or more of Ag, for example, 20% by weight or more, based on 100% by weight of the total negative electrode active material contained in the negative electrode active material layer, in the initial state without charging or discharging. can do.
한편, 음극 활물질층(24)에 포함된 음극 활물질에서 Ag 함량의 상한은 100 중량%일 수 있다. 그러나 Ag와 Li의 반응전위의 관계에서, Ag가 증가한다면 평균방전 전위가 낮아져 전지의 에너지 밀도도 저하될 수 있다. 따라서 고에너지 밀도화의 관점에서 Ag의 함량은 80 중량% 이하, 예를 들어 50 중량% 이하일 수 있다.Meanwhile, the upper limit of the Ag content in the negative electrode active material included in the negative electrode active material layer 24 may be 100% by weight. However, in the relationship between the reaction potentials of Ag and Li, if Ag increases, the average discharge potential may decrease and the energy density of the battery may also decrease. Therefore, from the viewpoint of high energy density, the Ag content may be 80% by weight or less, for example, 50% by weight or less.
음극 활물질층(24)에서 Ag 함량(중량%)은, 예를 들어 다음과 같이 측정할 수 있다. 즉, 전고체 리튬이온 이차전지(100)를 방전한 후에 이를 해체하고, 음극(20)의 표면으로부터 음극 활물질층(24)을 회수한다. 그리고 그 회수물 중의 Ag의 함량을 EDX, XRF 또는 ICP 등으로 구할 수 있다. 또한 예를 들어, 단면방향에서의 SEM-EDS 분석으로부터 Ag의 함량을 알 수 있다.The Ag content (% by weight) in the negative electrode active material layer 24 can be measured, for example, as follows. That is, after discharging the all-solid-state lithium ion secondary battery 100, it is dismantled, and the negative electrode active material layer 24 is recovered from the surface of the negative electrode 20. And the Ag content in the recovered product can be determined using EDX, XRF, or ICP. Also, for example, the Ag content can be known from SEM-EDS analysis in the cross-sectional direction.
또한 음극 활물질층(24)에서, 음극(20)의 적층방향에서 본 경우에 단위면적당 Ag의 함량이 너무 적으면, 방전시에 잔존하는 Ag도 줄어들기 때문에, 공극의 발생을 억제할 수 없게 될 우려가 있다. 따라서 음극 활물질층(24)에서 단위면적당 Ag의 함량은 0.05 mg/cm2 이상, 예를 들어 0.10 mg/cm2 이상일 수 있다.In addition, if the Ag content per unit area in the negative electrode active material layer 24 when viewed from the stacking direction of the negative electrode 20 is too small, the Ag remaining during discharge will also decrease, making it impossible to suppress the generation of voids. There are concerns. Therefore, the Ag content per unit area in the negative electrode active material layer 24 may be 0.05 mg/cm 2 or more, for example, 0.10 mg/cm 2 or more.
한편, 단위면적당 Ag의 함량이 너무 많으면, 평균 방전전위가 낮아져 전지의 에너지 밀도가 저하될 우려가 있다. 따라서 단위면적당 Ag의 함량은 5.0 mg/cm2 이하, 예를 들어 2.0 mg/cm2 이하일 수 있다.On the other hand, if the Ag content per unit area is too high, there is a risk that the average discharge potential will decrease and the energy density of the battery will decrease. Therefore, the Ag content per unit area may be 5.0 mg/cm 2 or less, for example, 2.0 mg/cm 2 or less.
음극 활물질층(24)의 단위면적당 Ag의 함량은, 예를 들어 다음과 같이하여 측정할 수 있다. 즉, 전고체 리튬이온 이차전지(100)를 방전 후에 이를 해체하고 음극(20)의 표면 또는 단면방향에서 SEM-EDS에서의 조성분석으로부터 Ag의 함량을 알 수 있다. 이에 한정되지 않고, XPS 및 ICP 등에서도 Ag의 함량을 알 수 있다.The Ag content per unit area of the negative electrode active material layer 24 can be measured, for example, as follows. That is, the all-solid lithium ion secondary battery 100 is dismantled after discharging, and the Ag content can be known from composition analysis by SEM-EDS on the surface or cross-sectional direction of the negative electrode 20. It is not limited to this, and the Ag content can also be known through XPS and ICP.
또한, 충방전을 하지 않은 초기 상태에서 음극 활물질층(24)이 포함하는 Ag은 입자 상 또는 막 상일 수 있다. 입자 상으로 존재하는 경우, Ag의 평균입자직경(d50)(직경길이 또는 평균직경)은 20 nm 내지 1 μm일 수 있으나, 이에 한정되지 않는다.Additionally, in the initial state without charging or discharging, Ag included in the negative electrode active material layer 24 may be in the form of particles or a film. When present in particle form, the average particle diameter (d50) (diameter length or average diameter) of Ag may be 20 nm to 1 μm, but is not limited thereto.
음극 활물질층(24)은 Ag 이외의 임의의 음극 활물질로서, 예를 들어, 비정질 탄소, Au, Pt, Pd, Si, Al, Bi, Sn, In 및 Zn으로부터 선택되는 1 종 이상을 더 포함할 수 있다. The negative electrode active material layer 24 is any negative electrode active material other than Ag, and may further include, for example, one or more types selected from amorphous carbon, Au, Pt, Pd, Si, Al, Bi, Sn, In, and Zn. You can.
음극 활물질층(24)에 포함되는 탄소재로는 비정질 탄소가 바람직하게 사용될 수 있다. 상기 비정질 탄소의 구체적인 예로는, 아세틸렌블랙, 퍼니스블랙 및 케첸블랙 등의 카본블랙, 그래핀, 또는 이들 조합을 들 수 있다.Amorphous carbon may be preferably used as the carbon material included in the negative electrode active material layer 24. Specific examples of the amorphous carbon include carbon black such as acetylene black, furnace black, and Ketjen black, graphene, or a combination thereof.
음극 활물질층(24)에 포함된 음극 활물질 전체 100 중량%를 기준으로, Ag 이외의 음극 활물질을 합쳐서 50 중량% 이상, 예를 들어 70 중량% 이상일 수 있다. Ag 이외의 음극 활물질의 함량은, 상기 Ag의 함량과 동일한 방법으로 측정할 수 있다.Based on 100% by weight of the total negative electrode active material included in the negative electrode active material layer 24, the total amount of negative electrode active materials other than Ag may be 50% by weight or more, for example, 70% by weight or more. The content of negative electrode active materials other than Ag can be measured in the same manner as the Ag content.
음극 활물질층(24)은 결착제(바인더)를 더 포함할 수 있다. 결착제(바인더)를 포함함으로써, 음극 활물질층(24)을 음극 집전체(22) 상에 안정화시킬 수 있다. 결착제(바인더)를 구성하는 재료로서는, 예를 들어, 스티렌부타디엔 고무(SBR), 폴리테트라플루오로에틸렌, 폴리불화비닐리덴, 폴리에틸렌 등의 수지재료를 들 수 있다. 결착제(바인더)는 이러한 수지 재료로부터 선택되는 1 종 이상으로 구성될 수 있다.The negative electrode active material layer 24 may further include a binder. By including a binder, the negative electrode active material layer 24 can be stabilized on the negative electrode current collector 22. Examples of materials constituting the binder (binder) include resin materials such as styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. The binder (binder) may be composed of one or more types selected from these resin materials.
또한 음극 활물질층(24)은 통상적인 전고체 리튬이온 이차전지에 사용되는 첨가제, 예를 들면 필러, 분산제, 이온도전제 등이 적절하게 배합되어 있어도 좋다. 상기 첨가제의 구체적인 예에 대해서는 전술한 양극에서 설명한 내용과 동일하다.Additionally, the negative electrode active material layer 24 may be appropriately mixed with additives used in conventional all-solid-state lithium ion secondary batteries, such as fillers, dispersants, and ion conductive agents. Specific examples of the additives are the same as those described for the above-mentioned positive electrode.
상기 음극 활물질층(24)의 전체 두께는 특별히 제한되지 않지만, 1 ㎛ 내지 100 ㎛, 또는 10 ㎛ 내지 60 ㎛일 수 있다. 상기 음극 활물질층(24)의 두께가 1 ㎛ 미만이 되는 경우, 전고체 이차전지의 성능이 충분히 개선되지 않을 수 있다. 상기 음극 활물질층(24)의 두께가 100 ㎛를 초과할 경우, 음극 활물질층(24)의 저항이 높아 결과적으로 전고체 이차전지의 성능이 충분히 개선되지 않을 수 있다. 상술한 바인더를 사용하면, 음극 활물질층(24)의 두께를 적정 수준으로 용이하게 확보할 수 있다.The total thickness of the negative electrode active material layer 24 is not particularly limited, but may be 1 ㎛ to 100 ㎛, or 10 ㎛ to 60 ㎛. If the thickness of the negative electrode active material layer 24 is less than 1 μm, the performance of the all-solid-state secondary battery may not be sufficiently improved. When the thickness of the negative electrode active material layer 24 exceeds 100 ㎛, the resistance of the negative electrode active material layer 24 is high, and as a result, the performance of the all-solid-state secondary battery may not be sufficiently improved. By using the above-described binder, the thickness of the negative electrode active material layer 24 can be easily secured at an appropriate level.
한편, 상기 음극 집전체(22) 상에 리튬과 합금 또는 화합물의 형성이 가능한 재료를 포함하는 막을 더 포함하고, 상기 막은 상기 음극 집전체(22) 와 상기 음극 활물질층 사이에 배치될 수 있다.Meanwhile, a film containing a material capable of forming an alloy or compound with lithium may be further included on the negative electrode current collector 22, and the film may be disposed between the negative electrode current collector 22 and the negative electrode active material layer.
상기 음극 집전체(22)는 리튬 금속과 반응하지 않지만 상부에 매끈한 리튬 금속층을 석출시키는 것을 어렵게 만들 수 있다. 상기 막은 리튬 금속이 상기 음극 집전체(22) 상부에 평탄하게 석출되게하는 습윤층(wetting layer)으로도 사용될 수 있다.Although the negative electrode current collector 22 does not react with lithium metal, it can make it difficult to deposit a smooth lithium metal layer on the top. The film can also be used as a wetting layer that allows lithium metal to precipitate evenly on the top of the negative electrode current collector 22.
상기 막에 사용되는 리튬 금속과 합금 형성이 가능한 재료로는 실리콘, 마그네슘, 알루미늄, 납, 은, 주석, 또는 이들 조합을 포함할 수 있다. 상기 막에 사용되는 리튬 금속과 화합물 형성이 가능한 재료는 탄소, 황화티타늄, 황화철, 또는 이들 조합을 포함할 수 있다. 상기 막에 사용된 재료의 함량은 전극의 전기화학적 성질 또는/및 전극의 산화환원 전위에 영향을 미치지 않는 한도 내에서 소량일 수 있다. 상기 막은 전고체 리튬이온 이차전지(100)의 충전 사이클 동안의 균열을 방지하기 위하여 상기 음극 집전체(22) 상에 평탄하게 적용될 수 있다. 상기 막의 적용은 증발 또는 스퍼터링과 같은 물리적 증착, 화학적 증착 또는 도금법 등의 방법이 사용될 수 있다.Materials capable of forming an alloy with lithium metal used in the film may include silicon, magnesium, aluminum, lead, silver, tin, or a combination thereof. Materials capable of forming a compound with lithium metal used in the film may include carbon, titanium sulfide, iron sulfide, or a combination thereof. The content of the material used in the membrane may be small as long as it does not affect the electrochemical properties of the electrode or/and the redox potential of the electrode. The film can be applied evenly on the negative electrode current collector 22 to prevent cracking during the charging cycle of the all-solid-state lithium ion secondary battery 100. The film may be applied using methods such as evaporation or sputtering, physical vapor deposition, chemical vapor deposition, or plating methods.
상기 막의 두께는 1 nm 내지 500 nm일 수 있다. 상기 막의 두께는 예를 들어, 2 nm 내지 400 nm일 수 있다. 상기 막의 두께는 예를 들어, 3 nm 내지 300 nm일 수 있다. 상기 막의 두께는 예를 들어, 4 nm 내지 200 nm일 수 있다. 상기 막의 두께는 예를 들어, 5 nm 내지 100 nm일 수 있다.The thickness of the film may be 1 nm to 500 nm. The thickness of the film may be, for example, 2 nm to 400 nm. The thickness of the film may be, for example, 3 nm to 300 nm. The thickness of the film may be, for example, 4 nm to 200 nm. The thickness of the film may be, for example, 5 nm to 100 nm.
(3) 고체 전해질층(3) Solid electrolyte layer
고체 전해질층(30)은 양극(10)과 음극(20) 사이(예를 들어, 양극 활물질층(14)과 음극 활물질층(24) 사이)에 배치되어 있다. 고체 전해질층(30)은 이온을 이동시킬 수 있는 고체 전해질을 포함한다. 상기 고체 전해질층(30)은 황화물계 고체 전해질을 포함할 수 있다.The solid electrolyte layer 30 is disposed between the positive electrode 10 and the negative electrode 20 (for example, between the positive electrode active material layer 14 and the negative electrode active material layer 24). The solid electrolyte layer 30 includes a solid electrolyte capable of moving ions. The solid electrolyte layer 30 may include a sulfide-based solid electrolyte.
상기 황화물계 고체 전해질은 Li2S-P2S5, Li2S-P2S5-LiX(X는 할로겐 원소), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn(m 및 n은 양수, Z는 Ge, Zn 또는 Ga 중에서 하나), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-LipMOq(p 및 q는 양수, M은 P, Si, Ge, B, Al, Ga 또는 In 중에서 하나), 또는 이들 조합을 포함할 수 있다. 고체 전해질은 이러한 황화물계 고체 전해질 재료에서 선택되는 1 종의 재료로 구성되어 있을 수도 있고, 2 종 이상의 재료로 구성되어 있을 수도 있다.The sulfide-based solid electrolyte is Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiX (X is a halogen element), Li 2 SP 2 S 5 -Li 2 O, Li 2 SP 2 S 5 -Li 2 O- LiI, Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m and n are positive numbers, Z is one of Ge, Zn or Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li p MO q (p and q are positive numbers, M is P, Si, Ge, B, Al, Ga or In), or a combination thereof. The solid electrolyte may be composed of one type of material selected from these sulfide-based solid electrolyte materials, or may be composed of two or more types of materials.
상기 황화물계 고체 전해질은 하기 화학식 1로 표시되는 고체 전해질을 포함할 수 있다:The sulfide-based solid electrolyte may include a solid electrolyte represented by the following formula (1):
<화학식 1><Formula 1>
LixM'yPSzAw Li x M'y PS z A w
상기 화학식 1에서,In Formula 1,
x, y, z, w는 서로 독립적으로 0 이상 6이하이고;x, y, z, and w are independently from 0 to 6;
M'는 As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, 또는 Ta 중에서 하나 이상이고;M' is one or more of As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta;
A는 F, Cl, Br, 또는 I 중에서 하나 이상이다.A is one or more of F, Cl, Br, or I.
고체 전해질로서 상기 황화물 고체 전해질 재료 중 구성원소로서 유황(S), 인(P) 및 리튬(Li)을 포함한 것을 이용할 수 있다. 예를 들어, Li2S-P2S5를 포함하는 것을 이용할 수 있다. 황화물계 고체 전해질 재료로서 Li2S-P2S5를 포함하는 것을 이용하는 경우, Li2S와 P2S5의 혼합 몰비는 예를 들어, Li2S:P2S5 = 50:50 ~ 90:10의 범위에서 선택될 수 있다.As a solid electrolyte, one containing sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the sulfide solid electrolyte materials can be used. For example, one containing Li 2 SP 2 S 5 may be used. When using a sulfide-based solid electrolyte material containing Li 2 SP 2 S 5 , the mixing molar ratio of Li 2 S and P 2 S 5 is, for example, Li 2 S:P 2 S 5 = 50:50 to 90: It can be selected from the range of 10.
또한 고체 전해질은 비정질 상태일 수도 있고, 결정질 상태일 수도 있다. 또한, 비정질 및 결정질이 섞인 상태일 수도 있다.Additionally, the solid electrolyte may be in an amorphous state or a crystalline state. Additionally, it may be in a mixed state of amorphous and crystalline.
고체 전해질층(30)은 결착제(바인더)를 더 포함할 수 있다. 상기 결착제(바인더) 재료로서 예를 들면, 스티렌부타디엔 고무(SBR), 폴리테트라플루오로에틸렌, 폴리불화비닐리덴, 폴리에틸렌, 폴리아크릴산 등의 수지를 들 수 있다. 상기 결착제(바인더) 재료로는 양극 활물질층(14)과 음극 활물질층(24) 내의 결착제(바인더)를 구성하는 재료와 동일할 수도 있고, 상이할 수도 있다.The solid electrolyte layer 30 may further include a binder. Examples of the binder (binder) material include resins such as styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polyacrylic acid. The binder material may be the same as or different from the material constituting the binder (binder) in the positive electrode active material layer 14 and the negative electrode active material layer 24.
(4) 초기 충전용량비(4) Initial charging capacity ratio
일 구현예에 따른 전고체 리튬이온 이차전지(100)는 음극 활물질층(24)의 초기 충전용량에 대하여 양극 활물질층(14)의 초기 충전용량이 과대하게 구성되어 있다. 후술하는 바와 같이, 일 구현예에 따른 전고체 리튬이온 이차전지(100)는 음극 활물질층(24)의 초기 충전용량을 초과하여 충전(즉 과충전)시켜 사용할 수 있다. 충전 초기에는 음극 활물질층(24)에 리튬이 흡장될 수 있다. 즉, 음극 활물질은 양극(10)에서 이동해 온 리튬이온 및 합금 또는 화합물을 형성할 수 있다. 음극 활물질층(24)의 초기 충전용량을 초과하여 충전이 행해지면 도 4에 도시된 바와 같이, 음극 활물질층(24)의 뒷면, 즉 음극 집전체(22)와 음극 활물질층(24) 사이에 리튬이 석출하여, 이 리튬에 의해 금속층(26)이 형성될 수 있다. 금속층(26)은 주로 Ag가 고용된 리튬(즉, Ag-Li 고용체)으로 구성될 수 있다. 이러한 현상은 음극 활물질, 예를 들어 리튬과 합금 또는 화합물을 형성하는 재료로 구성될 수 있다. 방전시에는 음극 활물질층(24) 및 금속층(26) 중의 리튬은 고용하고 있는 Ag를 잔존시킨 채 이온화하고 양극(10) 측으로 이동할 수 있다. 따라서 전고체 리튬이온 이차전지(100)에서 리튬을 음극 활물질로 사용할 수 있다. 또한, 음극 활물질층(24)은 금속층(26)을 코팅하기 때문에, 금속층(26)의 보호층으로 기능함과 동시에, 수지상 금속리튬의 석출 및 성장을 억제할 수 있다.In the all-solid lithium ion secondary battery 100 according to one embodiment, the initial charge capacity of the positive electrode active material layer 14 is excessive compared to the initial charge capacity of the negative electrode active material layer 24. As will be described later, the all-solid lithium ion secondary battery 100 according to one embodiment can be used by charging (i.e., overcharging) exceeding the initial charging capacity of the negative electrode active material layer 24. At the beginning of charging, lithium may be stored in the negative electrode active material layer 24. That is, the negative electrode active material can form an alloy or compound with lithium ions that have migrated from the positive electrode 10. When charging exceeds the initial charge capacity of the negative electrode active material layer 24, as shown in FIG. 4, the back side of the negative electrode active material layer 24, that is, between the negative electrode current collector 22 and the negative electrode active material layer 24. Lithium may precipitate, and the metal layer 26 may be formed by this lithium. The metal layer 26 may be mainly composed of lithium in which Ag is dissolved (i.e., Ag-Li solid solution). This phenomenon may consist of a negative electrode active material, for example, a material that forms an alloy or compound with lithium. During discharge, the lithium in the negative electrode active material layer 24 and the metal layer 26 is ionized and can move toward the positive electrode 10 while leaving the dissolved Ag remaining. Therefore, lithium can be used as a negative electrode active material in the all-solid lithium ion secondary battery 100. In addition, since the negative electrode active material layer 24 coats the metal layer 26, it functions as a protective layer for the metal layer 26 and can suppress precipitation and growth of dendritic metal lithium.
일 구현예에 따른 전고체 리튬이온 이차전지(100)는 음극 활물질층(24)의 초기 충전용량에 대한 양극 활물질층(14)의 초기 충전용량의 비, 즉 초기 충전용량비 b/a, 다음의 식 (100)을 만족하는 것이 바람직하다.The all-solid lithium ion secondary battery 100 according to one embodiment has the ratio of the initial charge capacity of the positive electrode active material layer 14 to the initial charge capacity of the negative electrode active material layer 24, that is, the initial charge capacity ratio b/a, as follows: It is desirable to satisfy equation (100).
0.01＜ b/a＜ 0.5 (100) 0.01 < b/a < 0.5 (100)
(여기서, a는 양극 활물질층(14)의 초기 충전용량(mAh)이며, b는 음극 활물질층(24)의 초기 충전용량(mAh)이다)(Here, a is the initial charge capacity (mAh) of the positive electrode active material layer 14, and b is the initial charge capacity (mAh) of the negative electrode active material layer 24)
초기 충전용량비가 0.01 이하인 경우, 전고체 리튬이온 이차전지(100)의 특성이 저하될 우려가 있다. 그 이유로는, 음극 활물질층(24)이 보호층으로서 충분히 기능하지 않는 것을 들 수 있다. 예를 들어, 음극 활물질층(24)의 두께가 매우 얇은 경우, 용량비가 0.01 이하로 될 수 있다. 이 경우, 충방전의 반복에 의해 음극 활물질층(24)이 붕괴되고 수지상 금속리튬이 석출 및 성장될 우려가 있다. 그 결과, 전고체 리튬이온 이차전지(100)의 특성이 저하될 수 있다. 따라서, 초기 충전용량비를 0.01 이상일 수 있다. 한편, 초기 충전용량비가 0.5 이상이 되면, 음극에서 리튬의 석출 량이 감소하기 때문에 전지용량이 줄어들 우려가 있다. 따라서, 초기 충전용량비는 0.5 미만일 수 있다.If the initial charge capacity ratio is 0.01 or less, there is a risk that the characteristics of the all-solid-state lithium ion secondary battery 100 may deteriorate. One reason for this is that the negative electrode active material layer 24 does not function sufficiently as a protective layer. For example, when the thickness of the negative electrode active material layer 24 is very thin, the capacity ratio may be 0.01 or less. In this case, there is a risk that the negative electrode active material layer 24 may collapse due to repeated charging and discharging, and dendritic lithium may precipitate and grow. As a result, the characteristics of the all-solid-state lithium ion secondary battery 100 may deteriorate. Therefore, the initial charge capacity ratio may be 0.01 or more. On the other hand, if the initial charge capacity ratio is more than 0.5, there is a risk that the battery capacity will decrease because the amount of lithium precipitation from the negative electrode decreases. Therefore, the initial charge capacity ratio may be less than 0.5.
(5) 전고체 리튬이온 이차전지의 구성(5) Composition of all-solid-state lithium-ion secondary battery
본 발명의 전고체 리튬이온 이차전지(100)는 양극(10), 고체 전해질층(30), 및 음극(20)을 이러한 순서로 포함하는 전고체 리튬이온 이차전지(100)이다. 상기 음극(20)은 음극 집전체(22) 및 음극 활물질층(24)을 포함하며, 상기 음극 활물질층(24)은 탄소재와 Ag를 포함하며, 2개 이상의 층을 포함하는이다.The all-solid lithium ion secondary battery 100 of the present invention is an all-solid lithium ion secondary battery 100 that includes a positive electrode 10, a solid electrolyte layer 30, and a negative electrode 20 in this order. The negative electrode 20 includes a negative electrode current collector 22 and a negative electrode active material layer 24, and the negative electrode active material layer 24 includes carbon material and Ag and includes two or more layers.
상기 음극 집전체(22)는 Ni 호일, Ni가 코팅된 Cu 호일, 스테인레스스틸 호일, 또는 이들 조합을 포함할 수 있다. 이러한 음극 집전체(22)는 방전용량이 더욱 향상될 수 있다.The negative electrode current collector 22 may include Ni foil, Ni-coated Cu foil, stainless steel foil, or a combination thereof. The discharge capacity of this negative electrode current collector 22 can be further improved.
<전고체 리튬이온 이차전지의 제조방법><Manufacturing method of all-solid-state lithium-ion secondary battery>
다음으로, 상기 전고체 리튬이온 이차전지(100)의 제조방법에 대하여 설명한다. 일 구현예에 따른 전고체 리튬이온 이차전지(100)는 양극(10), 음극(20), 및 고체 전해질층(30)을 각각 제작한 후, 위의 각 층을 적층함으로써 얻을 수 있다.Next, the manufacturing method of the all-solid-state lithium ion secondary battery 100 will be described. The all-solid lithium ion secondary battery 100 according to one embodiment can be obtained by manufacturing the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30, and then stacking each of the above layers.
(10) 양극 제작공정(10) Anode manufacturing process
양극 제작공정을 예를 들어 설명하면 다음과 같다. 먼저, 양극 활물질층(14)을 구성하는 재료(양극 활물질, 결착제(바인더) 등)를 비극성용매에 첨가하여 슬러리(또는 페이스트)를 제작한다. 이어서, 얻은 슬러리를 준비한 양극 집전체(12) 상에 도포한다. 이것을 건조시켜 적층체를 얻는다. 이어서 얻은 적층체를, 예를 들면 정수압을 이용하여 가압하여 양극(10)을 얻는다. 또한 가압 공정은 생략되어있다.The anode manufacturing process is explained with an example as follows. First, the materials constituting the positive electrode active material layer 14 (positive electrode active material, binder, etc.) are added to a non-polar solvent to produce a slurry (or paste). Next, the obtained slurry is applied onto the prepared positive electrode current collector 12. This is dried to obtain a laminate. Next, the obtained laminate is pressurized using, for example, hydrostatic pressure to obtain the anode 10. Additionally, the pressurizing process is omitted.
(20) 음극 제작공정 (20) Cathode manufacturing process
음극 제작공정을 예를 들어 설명하면 다음과 같다. 먼저, 음극 활물질층(24)을 구성하는 재료(Ag를 포함하는 음극 활물질, 결착제(바인더) 등)를 극성용매 또는 비극성용매에 첨가하여 슬러리(페이스트이어도 좋음)를 제조한다. 이어서, 얻은 슬러리를 준비한 음극 집전체(22) 상에 도포하여 제1층의 음극 활물질층을 형성다. 다음으로 상기 제1층과 Ag의 함량을 다르게 혼합한 슬러리(페이스트이어도 좋음)를 제조한다. 이어서, 얻은 슬러리를 상기 제2층 상부면에 도포하고 건조시켜 적층체를 얻는다.The cathode manufacturing process is explained with an example as follows. First, the materials constituting the negative electrode active material layer 24 (negative electrode active material containing Ag, binder, etc.) are added to a polar solvent or non-polar solvent to prepare a slurry (may be a paste). Next, the obtained slurry is applied on the prepared negative electrode current collector 22 to form a first layer of negative electrode active material. Next, a slurry (which may be a paste) is prepared by mixing the first layer with different amounts of Ag. Next, the obtained slurry is applied to the upper surface of the second layer and dried to obtain a laminate.
상기 음극 활물질층이 추가적으로 하나 이상의 층을 더 포함하는 경우, 위와 같은 방식으로 추가의 층을 적층할 수 있다.When the negative electrode active material layer further includes one or more layers, the additional layers can be laminated in the same manner as above.
이어서, 얻은 적층체를 예를 들면 정수압을 이용하여 가압함으로써 음극(20)을 제작한다. 또한 가압 공정은 생략되어도 좋다. 또한 슬러리를 음극 집전체(22)에 도포하는 방법은 특별히 한정되지 않고, 예를 들면, 스크린 인쇄법, 메탈 마스크 인쇄법, 정전 도장법, 딥코팅법, 스프레이 코팅법, 롤 코트법, 닥터 블레이드법, 그라비아 코팅법 등을 들 수 있다.Next, the cathode 20 is manufactured by pressurizing the obtained laminate using, for example, hydrostatic pressure. Additionally, the pressurizing process may be omitted. Additionally, the method of applying the slurry to the negative electrode current collector 22 is not particularly limited, and includes, for example, screen printing, metal mask printing, electrostatic coating, dip coating, spray coating, roll coating, and doctor blade method. , gravure coating method, etc.
상기에서 음극 활물질층을 2층으로 형성하는 방법을 설명하였으나, 추가의 층을 형성하는 경우에도 각 층을 형성할 슬러리를 제조하고, 위에 설명된 방법으로 적층 순서에 따라 순차적으로 각층을 적층하여 음극을 제조할 수 있다. Although the method of forming the negative electrode active material layer in two layers was described above, even when forming an additional layer, a slurry to form each layer is prepared, and each layer is sequentially stacked according to the stacking order by the method described above to form the negative electrode. can be manufactured.
(3) 고체 전해질층 제작 공정(3) Solid electrolyte layer manufacturing process
고체 전해질층(30)은 예를 들어, 황화물계 고체 전해질 재료를 포함하는 고체 전해질에 의해 제작할 수 있다.The solid electrolyte layer 30 can be manufactured using, for example, a solid electrolyte containing a sulfide-based solid electrolyte material.
먼저, 용융 급냉법이나 기계적 밀링법에 의해 출발원료 (예를 들어, Li2S, P2S5 등)를 처리하여 황화물계 고체 전해질 재료를 얻는다. 예를 들어, 용융 급냉법을 사용하는 경우, 출발원료를 소정량 혼합하고, 펠렛상으로 한 것을 진공 중에서 소정의 반응온도에서 반응시킨 후, 급냉하여 황화물계 고체 전해질 재료를 제조할 수 있다. 또한, Li2S와 P2S5의 혼합물의 반응온도는 400℃ ~ 1000℃, 예를 들어 800℃ ~ 900℃일 수 있다. 또한 반응시간은 0.1 시간 ~ 12 시간, 예를 들어 1 시간 ~ 12 시간일 수 있다. 또한 반응물의 급냉 온도는 10℃ 이하, 예를 들어 0℃ 이하일 수 있으며, 급냉속도는 통상 1℃/sec ~10000℃/sec, 예를 들어 1℃/sec ~ 1000℃/sec일 수 있다.First, starting raw materials (e.g., Li2S, P2S5, etc.) are processed by melt quenching or mechanical milling to obtain a sulfide-based solid electrolyte material. For example, when using the melt quenching method, a sulfide-based solid electrolyte material can be produced by mixing a predetermined amount of starting materials, forming pellets, reacting at a predetermined reaction temperature in a vacuum, and then quenching. Additionally, the reaction temperature of the mixture of Li 2 S and P 2 S 5 may be 400°C to 1000°C, for example, 800°C to 900°C. Additionally, the reaction time may be 0.1 hour to 12 hours, for example, 1 hour to 12 hours. Additionally, the quenching temperature of the reactant may be 10°C or lower, for example, 0°C or lower, and the quenching rate may generally be 1°C/sec to 10000°C/sec, for example, 1°C/sec to 1000°C/sec.
또한 기계적 밀링법을 사용하는 경우, 볼밀 등을 이용하여 출발원료를 교반시켜 반응시킴으로써, 황화물계 고체 전해질 재료를 제조할 수 있다. 또한, 기계적 밀링법의 교반속도 및 교반시간은 특별히 한정되지 않지만, 교반속도가 빠를수록 황화물계 고체 전해질 재료의 생성속도를 빠르게 할 수 있으며, 교반시간이 길수록 황화물계 고체 전해질 재료에 원료의 전환율을 높일 수 있다.Additionally, when using a mechanical milling method, a sulfide-based solid electrolyte material can be produced by stirring and reacting the starting materials using a ball mill or the like. In addition, the stirring speed and stirring time of the mechanical milling method are not particularly limited, but the faster the stirring speed, the faster the production rate of the sulfide-based solid electrolyte material, and the longer the stirring time, the higher the conversion rate of raw materials to the sulfide-based solid electrolyte material. It can be raised.
그 후, 얻어진 혼합원료(황화물계 고체 전해질 재료)를 소정온도에서 열처리한 후, 이를 분쇄하여 입자형상의 고체 전해질을 제조할 수 있다. 고체 전해질이 유리 전이점을 갖는 경우는, 열처리에 의해 비정질에서 결정질로 변하는 경우가 있다.Thereafter, the obtained mixed raw material (sulfide-based solid electrolyte material) is heat-treated at a predetermined temperature and then pulverized to produce a particle-shaped solid electrolyte. When a solid electrolyte has a glass transition point, it may change from amorphous to crystalline through heat treatment.
이어서, 상기 방법으로 얻어진 고체 전해질은, 예를 들면, 에어로졸 포지션법, 콜드 스프레이법, 스퍼터링법 등의 알려진 성막법을 이용하여 성막함으로써 고체 전해질층(30)을 제조할 수 있다. 또한, 고체 전해질층(30)은 고체 전해질 입자를 가압하여 제조될 수 있다. 또한 고체 전해질층(30)은 고체 전해질과 용매, 바인더를 혼합하여 도포 건조 가압함으로써 고체 전해질층(30)을 제조할 수 있다.Next, the solid electrolyte obtained by the above method can be used to form a film using known film forming methods such as the aerosol position method, cold spray method, and sputtering method, thereby producing the solid electrolyte layer 30. Additionally, the solid electrolyte layer 30 can be manufactured by pressing solid electrolyte particles. Additionally, the solid electrolyte layer 30 can be manufactured by mixing a solid electrolyte, a solvent, and a binder, applying, drying, and pressing.
(4) 적층공정(4) Lamination process
양극(10)과 음극(20) 사이에 고체 전해질층(30)을 배치하고, 이것을 예를 들면, 정수압 등을 이용하여 가압하여 일 구현예에 따른 전고체 리튬이온 이차전지(100)를 얻을 수 있다. An all-solid lithium ion secondary battery 100 according to one embodiment can be obtained by placing a solid electrolyte layer 30 between the anode 10 and the cathode 20 and pressurizing it using, for example, hydrostatic pressure. there is.
본 발명의 전고체 리튬이온 이차전지(100)는 엔드 플레이트 등을 이용하여 높은 외부 압력을 인가할 필요가 없고, 사용시에 양극(10), 음극(20) 및 고체 전해질층(30)에 인가된 외부압력이 1 MPa 이하라도, 향상된 방전용량을 제공할 수 있다.The all-solid-state lithium ion secondary battery 100 of the present invention does not need to apply high external pressure using an end plate, etc., and when used, the pressure applied to the positive electrode 10, the negative electrode 20, and the solid electrolyte layer 30 Even if the external pressure is less than 1 MPa, improved discharge capacity can be provided.
<전고체 리튬이온 이차전지의 충전방법><Charging method for all-solid-state lithium-ion secondary battery>
다음으로, 전고체 리튬이온 이차전지(100)의 충전방법에 대해 설명한다.Next, a charging method for the all-solid-state lithium ion secondary battery 100 will be described.
일 구현예에 따른 전고체 리튬이온 이차전지(100)의 충전방법은 전고체 리튬이온 이차전지(100)를 음극 활물질층(24)의 충전용량을 초과하여 충전(즉 과충전)하는 것일 수 있다.A method of charging the all-solid lithium ion secondary battery 100 according to one embodiment may be to charge the all-solid lithium ion secondary battery 100 beyond the charging capacity of the negative electrode active material layer 24 (i.e., overcharge).
충전 초기에는 음극 활물질층(24) 내에 리튬이 흡장될 수 있다. 음극 활물질층(24)의 충전용량을 초과하여 충전을 하면 도 4와 같이, 음극 활물질층(24)의 뒷면, 즉 음극 집전체(22)와 음극 활물질층(24) 사이에 리튬이 석출되고, 이 리튬에 의해 제조시에는 존재하지 않았던 금속층(26)이 형성될 수 있다. 방전시에는 음극 활물질층(24) 및 금속층(26) 중 리튬이 이온화되고 양극(10) 측으로 이동할 수 있다. 따라서 본 발명의 전고체 리튬이온 이차전지(100)에서는 리튬을 음극 활물질로 사용할 수 있다. 또한, 음극 활물질층(24)은 금속층(26)을 코팅하기 때문에, 금속층(26)의 보호층으로서 기능함과 동시에, 수지상 금속리튬의 석출 및 성장을 억제할 수 있다. 이렇게 하면, 전고체 리튬이온 이차전지(100)의 단락 및 용량 저하가 억제되고, 나아가 전고체 리튬이온 이차전지(100)의 특성이 향상될 수 있다. 또한, 일 구현예에 따르면, 금속층(26)은 미리 형성되어 있지 않기 때문에, 전고체 리튬이온 이차전지(100)의 제조비용을 줄일 수 있다.At the beginning of charging, lithium may be stored in the negative electrode active material layer 24. When charging exceeds the charging capacity of the negative electrode active material layer 24, lithium is precipitated on the back side of the negative electrode active material layer 24, that is, between the negative electrode current collector 22 and the negative electrode active material layer 24, as shown in FIG. This lithium can form a metal layer 26 that did not exist during manufacture. During discharge, lithium in the negative electrode active material layer 24 and the metal layer 26 is ionized and may move toward the positive electrode 10. Therefore, in the all-solid lithium ion secondary battery 100 of the present invention, lithium can be used as a negative electrode active material. Additionally, since the negative electrode active material layer 24 coats the metal layer 26, it functions as a protective layer for the metal layer 26 and can suppress precipitation and growth of dendritic metal lithium. In this way, short circuiting and capacity reduction of the all-solid-state lithium ion secondary battery 100 can be suppressed, and further, the characteristics of the all-solid-state lithium ion secondary battery 100 can be improved. Additionally, according to one embodiment, since the metal layer 26 is not formed in advance, the manufacturing cost of the all-solid-state lithium ion secondary battery 100 can be reduced.
또한, 금속층(26)은 도 4와 같이 음극 집전체(22)와 음극 활물질층(24) 사이에 형성되는 것에 한정하지 않고, 음극 활물질층(24)의 내부에 형성될 수도 있다. 또한, 금속층(26)이 음극 집전체(22)와 음극 활물질층(24) 사이 및 음극 활물질층(24)의 내부에 모두 형성되어 있을 수도 있다.In addition, the metal layer 26 is not limited to being formed between the negative electrode current collector 22 and the negative electrode active material layer 24 as shown in FIG. 4, and may be formed inside the negative electrode active material layer 24. Additionally, the metal layer 26 may be formed both between the negative electrode current collector 22 and the negative electrode active material layer 24 and inside the negative electrode active material layer 24.
본 발명의 전고체 리튬이온 이차전지(100)는 양극/세퍼레이터/음극의 구조를 갖는 단위 전지, 양극/세퍼레이터/음극/세퍼레이터/양극의 구조를 갖는 바이셀, 또는 단위 전지의 구조가 반복되는 적층 전지의 구조로 제작될 수 있다.The all-solid lithium ion secondary battery 100 of the present invention is a unit cell having a positive electrode/separator/negative electrode structure, a bicell having a positive electrode/separator/negative electrode/separator/positive electrode structure, or a stack in which the structure of the unit cells is repeated. It can be manufactured in the structure of a battery.
본 발명의 전고체 리튬이온 이차전지(100)의 형상은 특별히 한정되는 것은 아니며, 예를 들어 코인형, 버튼형, 시트형, 적층형, 원통형, 편평형, 뿔형 등을 예시할 수 있다. 또한 전기자동차 등에 이용하는 대형전지에도 적용될 수 있다. 예를 들어, 전고체 리튬이온 이차전지(100)는 플러그인하이브리드차량(plug-in hybrid electric vehicle, PHEV) 등의 하이브리드차량에도 사용될 수 있다. 또한, 많은 양의 전력 저장이 요구되는 분야에 사용될 수 있다. 예를 들어, 전기 자전거 또는 전동 공구 등에 사용될 수 있다.The shape of the all-solid-state lithium ion secondary battery 100 of the present invention is not particularly limited, and examples include coin shape, button shape, sheet shape, stacked shape, cylindrical shape, flat shape, and horn shape. It can also be applied to large batteries used in electric vehicles, etc. For example, the all-solid-state lithium ion secondary battery 100 can also be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEV). Additionally, it can be used in fields that require large amounts of power storage. For example, it can be used in electric bicycles or power tools.
이하, 본 발명을 구체적으로 설명하기 위해 실시예를 들어 상세하게 설명하기로 한다. 그러나 본 발명에 따른 실시예는 여러 가지 다른 형태로 변형될 수 있 으며, 본 발명의 범위가 아래에서 상술하는 실시예에 한정되는 것으로 해석되어서는 아니 된다. 본 발명의 실시예는 당업계에서 평균적인 지식을 가진 자에게 본 발명을 보다 완전하게 설명하기 위해서 제공되는 것이다.Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described in detail below. Examples of the present invention are provided to more completely explain the present invention to those with average knowledge in the art.
비교예 1: 음극 제조Comparative Example 1: Cathode Preparation
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 카본블랙 6g, 입경(D50)이 40nm 내지 60nm인 Ag 2g, PVdF 바인더(고형분 6%) 9.33g, 및 NMP 용액 7.67g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 음극 활물질 슬러리를 제조하였다.An amorphous carbon material containing 6 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 2 g of Ag with a particle size (D50) of 40 nm to 60 nm, 9.33 g of PVdF binder (solid content 6%), and 7.67 g of NMP solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, an additional 5 g of NMP solution was added and mixed five times for 3 minutes each at 2000 rpm to prepare a negative electrode active material slurry.
이후, SUS 호일에 상기 슬러리를 60㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Afterwards, the slurry was coated on SUS foil to a thickness of 60㎛ and dried to prepare a negative electrode.
실시예 1: 음극 제조Example 1: Cathode Preparation
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 3g, 입경(D50)이 40nm 내지 60nm인 Ag 1.33g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제1 음극 활물질 슬러리를 제조하였다. An amorphous carbon material containing 3 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 1.33 g of Ag with a particle size (D50) of 40 nm to 60 nm, 4.67 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 3g, 입경(D50)이 40nm 내지 60nm인 Ag 0.66g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제2 음극 활물질 슬러리를 제조하였다.An amorphous carbon material containing 3 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 0.66 g of Ag with a particle size (D50) of 40 nm to 60 nm, 4.67 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
이후, SUS 호일에 상기 제1 음극 활물질 슬러리를 30㎛ 두께로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 30㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Thereafter, the first negative electrode active material slurry was coated to a thickness of 30 μm on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 30 μm on the upper surface of the first negative electrode active material layer formed by the coating and dried. A cathode was prepared.
실시예 2: 음극 제조Example 2: Cathode Preparation
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 3g, 입경(D50)이 40nm 내지 60nm인 Ag 2g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제1 음극 활물질 슬러리를 제조하였다. An amorphous carbon material containing 3 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 2 g of Ag with a particle size (D50) of 40 nm to 60 nm, 4.67 g of PVdF binder (solid content 6%), and NMP solution. 1.5 g was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 3g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제2 음극 활물질 슬러리를 제조하였다.3 g of carbon black, an amorphous carbon material with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 4.67 g of PVdF binder (solid content 6%), and 1.5 g of NMP solution were placed in a Thinky mixer container and mixed at 2000 rpm for 3 minutes each. Mixed 12 times. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
이후, SUS 호일에 상기 제1 음극 활물질 슬러리를 30㎛ 두께로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 30㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Thereafter, the first negative electrode active material slurry was coated to a thickness of 30 μm on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 30 μm on the upper surface of the first negative electrode active material layer formed by the coating and dried. A cathode was prepared.
실시예 3: 음극 제조Example 3: Cathode Preparation
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 2g, 입경(D50)이 40nm 내지 60nm인 Ag 1.33g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제1 음극 활물질 슬러리를 제조하였다. An amorphous carbon material containing 2 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 1.33 g of Ag with a particle size (D50) of 40 nm to 60 nm, 3.11 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 2g, 입경(D50)이 40nm 내지 60nm인 Ag 0.66g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제2 음극 활물질 슬러리를 제조하였다.An amorphous carbon material containing 2 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 0.66 g of Ag with a particle size (D50) of 40 nm to 60 nm, 3.11 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 2g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제3 음극 활물질 슬러리를 제조하였다.2 g of carbon black, an amorphous carbon material with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 3.11 g of PVdF binder (solid content 6%), and 1.5 g of NMP solution were placed in a Thinky mixer container and mixed at 2000 rpm for 3 minutes each. Mixed 12 times. Afterwards, 5 g of NMP solution was additionally added and mixed five times for 3 minutes each at 2000 rpm to prepare a third negative electrode active material slurry.
이후, SUS 호일에 상기 제1 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조하였다.Afterwards, the first negative electrode active material slurry was coated on a SUS foil to a thickness of 20㎛ and dried, and then the second negative electrode active material slurry was coated at a thickness of 20㎛ on the upper surface of the first negative electrode active material layer formed by the coating and dried. .
다음으로, 상기 코팅에 의해 형성된 제2 음극 활물질층의 상부면에 상기 제3 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Next, the third negative electrode active material slurry was coated to a thickness of 20 μm on the upper surface of the second negative electrode active material layer formed by the coating and dried to prepare a negative electrode.
실시예 4: 음극 제조Example 4: Cathode Preparation
실시예 1에서 SUS 호일에 상기 제1 음극 활물질 슬러리를 40㎛ 두께(실시예 1: 30㎛)로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 20㎛ 두께(실시예 1: 30㎛)로 코팅하고 건조한 것을 제외하고는, 실시예 1과 동일한 방법으로 음극을 제조하였다.In Example 1, the first negative electrode active material slurry was coated on a SUS foil to a thickness of 40㎛ (Example 1: 30㎛) and dried, and then the second negative electrode active material was applied to the upper surface of the first negative electrode active material layer formed by the coating. A negative electrode was manufactured in the same manner as in Example 1, except that the slurry was coated to a thickness of 20 μm (Example 1: 30 μm) and dried.
실시예 5: 음극 제조Example 5: Cathode Preparation
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 2g, 입경(D50)이 40nm 내지 60nm인 Ag 1.33g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제1 음극 활물질 슬러리를 제조하였다. An amorphous carbon material containing 2 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 1.33 g of Ag with a particle size (D50) of 40 nm to 60 nm, 3.11 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 2g, 입경(D50)이 40nm 내지 60nm인 Ag 0.66g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제2 음극 활물질 슬러리를 제조하였다.An amorphous carbon material containing 2 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 0.66 g of Ag with a particle size (D50) of 40 nm to 60 nm, 3.11 g of PVdF binder (6% solid content), and NMP. 1.5 g of the solution was placed in a Thinky mixer container and mixed 12 times at 2000 rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
입경(D50)이 40nm 내지 60nm인 Ag 2-5g, PVdF 바인더(고형분 6%) 3.11g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제3 음극 활물질 슬러리를 제조하였다.2-5 g of Ag with a particle diameter (D50) of 40 nm to 60 nm, 3.11 g of PVdF binder (solid content 6%), and 1.5 g of NMP solution were placed in a Thinky mixer container and mixed 12 times for 3 minutes each at 2000 rpm. Afterwards, 5 g of NMP solution was additionally added and mixed five times for 3 minutes each at 2000 rpm to prepare a third negative electrode active material slurry.
이후, SUS 호일에 상기 제3 음극 활물질 슬러리를 10 ㎛ 두께로 코팅하고 건조한 후, 상기 제3 코팅층의 상부면에 제1 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Thereafter, the third negative electrode active material slurry was coated to a thickness of 10 ㎛ on the SUS foil and dried, and then the first negative electrode active material slurry was coated to a thickness of 20 μm on the upper surface of the third coating layer and dried, and then the first negative electrode active material slurry formed by the coating was coated and dried. 1 The second negative electrode active material slurry was coated to a thickness of 20㎛ on the upper surface of the negative electrode active material layer and dried to prepare a negative electrode.
실시예 6:Example 6:
음극 제조cathode manufacturing
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 6g, 입경(D50)이 40nm 내지 60nm인 Ag 6g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g 을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제1 음극 활물질 슬러리를 제조하였다. An amorphous carbon material containing 6 g of carbon black with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 6 g of Ag with a particle size (D50) of 40 nm to 60 nm, 4.67 g of PVdF binder (solid content 6%), and NMP solution. 1.5g was placed in a Thinky mixer container and mixed 12 times at 2000rpm for 3 minutes each. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a first negative active material slurry.
비정질 탄소재로서 입경(D50)이 40nm 내지 60nm이고 산소의 함량이 5.2 at%인 카본블랙 6g, PVdF 바인더(고형분 6%) 4.67g, 및 NMP 용액 1.5g을 Thinky mixer 용기에 넣고 2000rpm으로 3분씩 12번 믹싱하였다. 이후, NMP 용액 5g을 추가로 투입한 후 2000rpm으로 3분씩 5번 믹싱하여 제2 음극 활물질 슬러리를 제조하였다.6 g of carbon black, an amorphous carbon material with a particle size (D50) of 40 nm to 60 nm and an oxygen content of 5.2 at%, 4.67 g of PVdF binder (solid content 6%), and 1.5 g of NMP solution were placed in a Thinky mixer container and mixed at 2000 rpm for 3 minutes each. Mixed 12 times. Afterwards, 5 g of NMP solution was additionally added and mixed 5 times at 2000 rpm for 3 minutes each to prepare a second negative active material slurry.
이후, SUS 호일에 상기 제1 음극 활물질 슬러리를 20㎛ 두께로 코팅하고 건조한 후, 상기 코팅에 의해 형성된 제1 음극 활물질층의 상부면에 상기 제2 음극 활물질 슬러리를 40㎛ 두께로 코팅하고 건조하여 음극을 제조하였다.Thereafter, the first negative electrode active material slurry was coated to a thickness of 20 μm on the SUS foil and dried, and then the second negative electrode active material slurry was coated to a thickness of 40 μm on the upper surface of the first negative electrode active material layer formed by the coating and dried. A cathode was prepared.
실시예 7 및 비교예 2의 전고체 리튬이온 이차전지의 제조Preparation of all-solid lithium ion secondary battery of Example 7 and Comparative Example 2
양극으로는 양극활물질이 집전체에 5mAh/cm2로 로딩된 양극을 사용하고, 음극으로는 실시예 6 및 비교예 1에서 제조된 음극을 사용하고, 전해질로는 황화물계 전고체 전해질을 사용하여 실시예 7 및 비교예 2의 파우치형 모노셀을 제작하였다. As the positive electrode, a positive electrode in which the positive electrode active material was loaded at 5 mAh/cm 2 on the current collector was used, and as the negative electrode, the positive electrode prepared in Example 6 and Comparative Example 1 was used. The pouch-type monocell of Example 7 and Comparative Example 2 was manufactured using a negative electrode and a sulfide-based all-solid electrolyte as the electrolyte.
실험예 1: 전지의 특성 평가Experimental Example 1: Evaluation of battery characteristics
상기 실시예 7 및 비교예 2의 파우치형 모노셀을 작동전압 범위 4.25V-3.0V 및 구동온도 60℃에서 다음의 충방전 조건으로 구동시켜 사이클 특성을 평가하고 그 결과를 도 6에 나타내었다.The pouch-type monocell of Example 7 and Comparative Example 2 was driven under the following charge/discharge conditions at an operating voltage range of 4.25V-3.0V and a drive temperature of 60°C to evaluate cycle characteristics, and the results are shown in FIG. 6.
충전조건: 0.33C, 4.25V CC/CV, 0.1C cut-off Charging conditions: 0.33C, 4.25V CC/CV, 0.1C cut-off
방전조건: 0.33C, 3.0V, CCDischarge conditions: 0.33C, 3.0V, CC
도 5로부터, 실시예 7 전지의 경우 비교예 2의 전지와 비교하여 사이클이 진행됨에 따라 셀용량의 큰 저하없이 구동됨을 확인할 수 있다.From Figure 5, it can be seen that the battery of Example 7 operates without a significant decrease in cell capacity as the cycle progresses compared to the battery of Comparative Example 2.
도 6은 상기 실시예 6의 음극에 대한 SEM 이미지를 나타낸다. 도 6에서 확인되는 바와 같이, 실시예 6의 음극은 집전체에 가까운 활물질층에 Ag 입자가 많이 배치된 것을 확인할 수 있으며, 상기 실시예 7의 전지는 이러한 구조를 갖는 음극을 포함함으로써 사이클 특성이 향상된 것으로 보인다. Figure 6 shows an SEM image of the cathode of Example 6. As can be seen in Figure 6, it can be seen that the negative electrode of Example 6 has many Ag particles disposed in the active material layer close to the current collector, and the battery of Example 7 includes a negative electrode with this structure, so that the cycle characteristics are improved. It appears to have improved.
실험예 2: 탄소재-Ag 복합체의 입도 측정Experimental Example 2: Measurement of particle size of carbon material-Ag composite
(1) 탄소재-금속 복합체 시료 분리(1) Separation of carbon material-metal composite samples
상기 실시예 1의 제1 음극 활물질 슬러리, 및 산소의 함량이 5.2 at%인 카본블랙 대신 산소의 함량이 2.6 at%인 카본블랙을 사용한 것으로 제외하고는 실시예 1의 제1 음극 활물질 슬러리와 동일한 방법으로 제조된 비교예 2의 음극 활물질 슬러리에 포함된 탄소재-금속 복합체 일부를 취하여 NMP 용액에 희석하여 분석 시료를 준비하였다.The same as the first anode active material slurry of Example 1, except that carbon black with an oxygen content of 2.6 at% was used instead of carbon black with an oxygen content of 5.2 at%. A portion of the carbon material-metal composite contained in the negative electrode active material slurry of Comparative Example 2 prepared by the method was taken and diluted in NMP solution to prepare an analysis sample.
(2) 분석기기(2) Analysis equipment
입도분석기 모델명 Mastersizer 3000(Malvem panalytical)를 사용하여 입도 분석을 진행하였다. 구체적으로 상기 (1)에서 준비한 탄소재-금속 복합체 분석 시료 1(실시예 1, 산소함량 5.2 at%인 카본블랙 포함) 및 탄소재-금속 복합체 분석 시료 2(산소함량 2.6 at%인 카본블랙 포함)를 각각 laser obscuration의 10-15%가 되도록 상기 장치의 샘플 투입구에 넣고 측정을 진행하였다.Particle size analysis was performed using a particle size analyzer model name Mastersizer 3000 (Malvem panalytical). Specifically, carbon material-metal composite analysis sample 1 (Example 1, including carbon black with an oxygen content of 5.2 at%) and carbon material-metal composite analysis sample 2 (including carbon black with an oxygen content of 2.6 at%) prepared in (1) above. ) was placed into the sample inlet of the device to be 10-15% of the laser obscuration, and the measurement was performed.
상기 분석기기는 입도 범위 0.01㎛ 내지 3500㎛까지 분석이 가능하며, 레이저 회절을 통해 습식과 건식 형태의 분산 유형에 적합한 입도 분석기이다.The analysis device is capable of analyzing particle sizes ranging from 0.01㎛ to 3500㎛, and is a particle size analyzer suitable for wet and dry dispersion types through laser diffraction.
(3) 분석결과(3) Analysis results
상기 탄소재-금속 복합체 분석 시료 1 및 시료 2의 입도 분석결과를 하기 표 1 및 도 6에 나타내었다. The particle size analysis results of the carbon material-metal composite analysis sample 1 and sample 2 are shown in Table 1 and Figure 6 below.
| D10(㎛)D10(㎛) | D50(㎛)D50(㎛) | D90(㎛)D90(㎛) | |
| 탄소재-금속 복합체 분석 시료 1(산소함량: 5.2 at%인 카본블랙 포함)Carbon material-metal composite analysis sample 1 (including carbon black with oxygen content: 5.2 at%) | 0.0190.019 | 0.2610.261 | 0.6230.623 |
| 탄소재-금속 복합체 분석 시료 2(산소함량: 2.6 at%인 카본블랙 포함)Carbon material-metal composite analysis sample 2 (including carbon black with oxygen content: 2.6 at%) | 3.143.14 | 8.268.26 | 18.318.3 |
상기 표 1의 결과로부터, 산소함량이 5.2 at%인 카본블랙을 포함한 탄소재-금속 복합체의 입도는 산소함량이 2.6 at%인 카본블랙을 포함한 탄소재-금속 복합체의 입도와 비교하여 현저히 작은 것을 알 수 있다. 또한, 도 3에 도시된 분석결과에 따르면, 산소함량이 5.2 at%인 카본블랙을 포함한 탄소재-금속 복합체의 최대 입도는 1㎛ 이하로서, 산소함량이 2.6 at%인 카본블랙을 포함한 탄소재-금속 복합체의 입도와 비교하여 현저히 작은 것을 알 수 있다. From the results in Table 1, the particle size of the carbon material-metal composite containing carbon black with an oxygen content of 5.2 at% is significantly smaller than that of the carbon material-metal composite containing carbon black with an oxygen content of 2.6 at%. Able to know. In addition, according to the analysis results shown in Figure 3, the maximum particle size of the carbon material-metal composite containing carbon black with an oxygen content of 5.2 at% is 1㎛ or less, and the carbon material containing carbon black with an oxygen content of 2.6 at% is 1㎛ or less. -You can see that it is significantly smaller compared to the particle size of the metal composite.
Claims (15)
- 양극, 음극, 및 상기 양극 및 음극 사이에 개재된 고체 전해질을 포함하며, It includes an anode, a cathode, and a solid electrolyte interposed between the anode and the cathode,상기 음극은 음극 집전체와 음극 활물질층을 포함하며, The negative electrode includes a negative electrode current collector and a negative electrode active material layer,상기 음극 활물질층은 탄소재와 Ag를 포함하며, 2개 이상의 층을 포함하는 전고체 리튬이온 이차전지.The anode active material layer includes carbon material and Ag, and is an all-solid lithium ion secondary battery comprising two or more layers.
- 제1항에 있어서,According to paragraph 1,상기 2개 이상의 층은 탄소재와 Ag를 포함하는 2개의 층을 포함하며,The two or more layers include two layers containing carbon material and Ag,상기 2개의 층은 서로 다른 Ag 함량을 갖는 것을 특징으로 하는 전고체 리튬이온 이차전지. An all-solid lithium ion secondary battery, characterized in that the two layers have different Ag contents.
- 제2항에 있어서,According to paragraph 2,상기 탄소재와 Ag를 포함하는 2개의 층 중 음극 집전체에 인접하여 배치되는 층이 고체 전해질에 인접하여 배치되는 층보다 Ag 함량 비율이 더 높은 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, wherein among the two layers containing the carbon material and Ag, the layer disposed adjacent to the negative electrode current collector has a higher Ag content ratio than the layer disposed adjacent to the solid electrolyte.
- 제3항에 있어서,According to clause 3,상기 음극 집전체에 인접하여 배치되는 층은 상기 고체 전해질에 인접하여 배치되는 층보다 1.5배 내지 10배의 Ag를 포함하는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, wherein the layer disposed adjacent to the negative electrode current collector contains 1.5 to 10 times more Ag than the layer disposed adjacent to the solid electrolyte.
- 제3항에 있어서,According to clause 3,상기 탄소재와 Ag를 포함하는 2개의 층은 각각 독립적으로 1㎛ 내지 50㎛의 두께를 갖는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, characterized in that the two layers containing the carbon material and Ag each independently have a thickness of 1㎛ to 50㎛.
- 제3항에 있어서,According to clause 3,상기 탄소재와 Ag를 포함하는 2개의 층 이외에 음극 활물질 전체 100 중량%를 기준으로 Ag 0 내지 5 중량%와 탄소재를 포함하는 층을 더 포함하는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, in addition to the two layers containing the carbon material and Ag, further comprising a layer containing 0 to 5% by weight of Ag and a carbon material based on 100% by weight of the total negative electrode active material.
- 제6항에 있어서,According to clause 6,상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층은 Ag를 포함하지 않는 층인 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, wherein the layer containing 0 to 5% by weight of Ag and a carbon material is a layer that does not contain Ag.
- 제6항에 있어서,According to clause 6,상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층은 상기 탄소재와 Ag를 포함하는 2개의 층 사이에 배치되거나, 상기 2개의 층 중 고체 전해질 인접층과 고체 전해질 사이에 배치되는 것을 특징으로 하는 전고체 리튬이온 이차전지.The layer containing 0 to 5% by weight of Ag and a carbon material is disposed between two layers containing the carbon material and Ag, or between a solid electrolyte adjacent layer and a solid electrolyte among the two layers. All-solid-state lithium-ion secondary battery.
- 제8항에 있어서,According to clause 8,상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층은 상기 2개의 층 중 고체 전해질 인접층과 고체 전해질 사이에 배치되는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, characterized in that the layer containing 0 to 5% by weight of Ag and a carbon material is disposed between the solid electrolyte adjacent layer and the solid electrolyte among the two layers.
- 제6항에 있어서, According to clause 6,상기 Ag 0 내지 5 중량%와 탄소재를 포함하는 층은 1㎛ 내지 30㎛의 두께를 갖는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, characterized in that the layer containing 0 to 5% by weight of Ag and a carbon material has a thickness of 1㎛ to 30㎛.
- 제3항에 있어서,According to clause 3,상기 탄소재와 Ag를 포함하는 2개의 층 이외에 음극 활물질 전체 100 중량%를 기준으로 Ag를 80 내지 100 중량%로 포함하는 층을 더 포함하는 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, characterized in that, in addition to the two layers containing the carbon material and Ag, it further comprises a layer containing 80 to 100% by weight of Ag based on 100% by weight of the total negative electrode active material.
- 제11항에 있어서,According to clause 11,상기 음극 활물질 전체 100 중량%를 기준으로 Ag를 80 내지 100 중량%로 포함하는 층은 상기 2개의 층 중 음극 집전체와 인접한 층과 음극 집전체 사이에 배치되는 것을 특징으로 하는 전고체 리튬이온 이차전지.The layer containing 80 to 100% by weight of Ag based on 100% by weight of the total negative electrode active material is an all-solid lithium ion secondary, characterized in that it is disposed between the negative electrode current collector and a layer adjacent to the negative electrode current collector among the two layers. battery.
- 제1항에 있어서,According to paragraph 1,상기 2개 이상의 층은 탄소재와 Ag를 포함하는 1개의 층 및 Ag 0 내지 5 중량%와 탄소재를 포함하는 1개의 층을 포함하는 것을 특징으로 하는 전고체 리튬이온 이차전지. An all-solid lithium ion secondary battery, wherein the two or more layers include one layer containing carbon material and Ag and one layer containing 0 to 5% by weight of Ag and carbon material.
- 제1항에 있어서, According to paragraph 1,상기 양극은 양극 집전체와 양극 활물질층을 포함하는 것을 특징으로 하는 전고체 리튬이온 이차전지.The positive electrode is an all-solid lithium ion secondary battery, characterized in that it includes a positive electrode current collector and a positive electrode active material layer.
- 제1항에 있어서, According to paragraph 1,상기 고체 전해질은 황화물계 고체 전해질인 것을 특징으로 하는 전고체 리튬이온 이차전지.An all-solid lithium ion secondary battery, wherein the solid electrolyte is a sulfide-based solid electrolyte.
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| KR20200134126A (en) * | 2019-05-21 | 2020-12-01 | 삼성전자주식회사 | All solid lithium secondary battery and charging method for the same |
| EP3869584A1 (en) * | 2020-02-18 | 2021-08-25 | Samsung Electronics Co., Ltd. | All-solid secondary battery, and method of manufacturing allsolid secondary battery |
| KR20210113878A (en) * | 2020-03-09 | 2021-09-17 | 삼성전자주식회사 | All Solid secondary battery, and method for preparing all solid secondary battery |
| US20220045354A1 (en) * | 2020-08-06 | 2022-02-10 | Samsung Electronics Co., Ltd. | All-solid secondary battery and method of manufacturing the same |
| CN115084638A (en) * | 2022-06-02 | 2022-09-20 | 中国第一汽车股份有限公司 | Solid-state electrode unit, preparation method, solid-state battery and system thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20200134126A (en) * | 2019-05-21 | 2020-12-01 | 삼성전자주식회사 | All solid lithium secondary battery and charging method for the same |
| EP3869584A1 (en) * | 2020-02-18 | 2021-08-25 | Samsung Electronics Co., Ltd. | All-solid secondary battery, and method of manufacturing allsolid secondary battery |
| KR20210113878A (en) * | 2020-03-09 | 2021-09-17 | 삼성전자주식회사 | All Solid secondary battery, and method for preparing all solid secondary battery |
| US20220045354A1 (en) * | 2020-08-06 | 2022-02-10 | Samsung Electronics Co., Ltd. | All-solid secondary battery and method of manufacturing the same |
| CN115084638A (en) * | 2022-06-02 | 2022-09-20 | 中国第一汽车股份有限公司 | Solid-state electrode unit, preparation method, solid-state battery and system thereof |
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